天梯赛备赛刷题记录(4.18)

蓝桥杯打完了，打的确实lj，好好备天梯赛
备赛分为总体两部分 1.基础强化训练 2. 真题模拟

4.10

1097. 池塘计数

dfs

#include 
using namespace std;
const int N=1010;
char g[N][N];
int dx[8]={-1,-1,-1,0,0,1,1,1};
int dy[8]={-1,0,1,-1,1,-1,0,1};
int n,m;
int cnt;
void dfs(int x,int y)
{
    g[x][y]='.';
    for(int i=0;i<8;i++)
    {
        int a=dx[i]+x,b=dy[i]+y;
        if(a<0||a>=n||b<0||b>=m)continue;
        if(g[a][b]=='.')continue;
        dfs(a,b);
    }
}
int main()
{
    cin>>n>>m;
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<m;j++)
        {
            cin>>g[i][j];
        }
    }
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<m;j++)
        {
            if(g[i][j]=='W')
            {
                dfs(i,j);
                cnt++;
            }
            
        }
    }
    cout<<cnt<<endl;
    return 0;
}

bfs

#include 
using namespace std;
const int N=1010;
typedef pair<int,int>PII;
char g[N][N];
int dx[8]={-1,-1,-1,0,0,1,1,1};
int dy[8]={-1,0,1,-1,1,-1,0,1};
int n,m;
int cnt;
void bfs(int x,int y)
{
    queue<PII>q;
    q.push({x,y});
    g[x][y]='.';
    while(q.size())
    {
        auto t=q.front();
        q.pop();
        int x=t.first,y=t.second;
        for(int i=0;i<8;i++)
        {
            int a=x+dx[i],b=y+dy[i];
            if(a<0||a>=n||b<0||b>=m)continue;
            if(g[a][b]=='.')continue;
            q.push({a,b});
            g[a][b]='.';
        }
    }
}
int main()
{
    cin>>n>>m;
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<m;j++)
        {
            cin>>g[i][j];
        }
    }
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<m;j++)
        {
            if(g[i][j]=='W')
            {
                bfs(i,j);
                cnt++;
            }
        }
    }
    cout<<cnt<<endl;
    return 0;
}

1098. 城堡问题

#include 
#define x first
#define y second
using namespace std;
typedef pair<int,int>PII;
const int N=55;
int n,m;
int g[N][N];
bool st[N][N];
int dx[4]={0,-1,0,1};
int dy[4]={-1,0,1,0};
int area,cnt;
int bfs(int x,int y)
{
    queue<PII>q;
    q.push({x,y});
    st[x][y]=true;
    int s=0;
    while(q.size())
    {
        auto t=q.front();
        q.pop();
        s++;
        for(int i=0;i<4;i++)
        {
            int a=dx[i]+t.x,b=dy[i]+t.y;
            if(a<0||a>=n||b<0||b>=m)continue;
            if(st[a][b])continue;
            if(g[t.x][t.y]>>i&1)continue;
            q.push({a,b});
            st[a][b]=true;
        }
    }
    return s;
}
int main()
{
    cin>>n>>m;
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<m;j++)
        {
            cin>>g[i][j];
        }
    }
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<m;j++)
        {
            if(!st[i][j])
            {
                cnt++;
                area=max(area,bfs(i,j));
            }
        }
    }
    cout<<cnt<<endl;
    cout<<area<<endl;
    return 0;
}

1106. 山峰和山谷

#include 
#define x first
#define y second
using namespace std;
typedef pair<int,int>PII;
const int N=1010;
int dx[8]={-1,-1,-1,0,0,1,1,1};
int dy[8]={-1,0,1,1,-1,1,0,-1};
int g[N][N];
bool st[N][N];
int n;
int peak,valley;
void bfs(int x,int y,bool &has_higher,bool &has_lower)
{
    queue<PII>q;
    q.push({x,y});
    st[x][y]=true;
    while(q.size())
    {
        auto t=q.front();
        q.pop();
        for(int i=0;i<8;i++)
        {
            int a=dx[i]+t.x,b=dy[i]+t.y;
            if(a<0||a>=n||b<0||b>=n)continue;
            if(g[a][b]>g[t.x][t.y])has_higher=true;
            else if(g[a][b]<g[t.x][t.y])has_lower=true;
            else if(!st[a][b])
            {
                q.push({a,b});
                st[a][b]=true;
            }
        }
    }
}
int main()
{
    cin>>n;
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<n;j++)
        {
            cin>>g[i][j];
        }
    }
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<n;j++)
        {
            if(!st[i][j])
            {
                bool has_lower=false,has_higher=false;
                bfs(i,j,has_higher,has_lower);
                if(!has_lower)valley++;
                if(!has_higher)peak++;
            }
        }
    }
    cout<<peak<<' '<<valley<<endl;
    return 0;
}

1706. 迷宫问题

#include 
#define x first
#define y second
using namespace std;
typedef pair<int,int>PII;
const int N=1010;
int dx[4]={0,-1,0,1};
int dy[4]={-1,0,1,0};
int g[N][N];
bool st[N][N];
PII pre[N][N];
int n;
void bfs()
{
    queue<PII>q;
    q.push({0,0});
    st[0][0]=true;
    while(q.size())
    {
        auto t=q.front();
        q.pop();
        for(int i=0;i<4;i++)
        {
            int a=dx[i]+t.x,b=dy[i]+t.y;
            if(a<0||a>=n||b<0||b>=n)continue;
            if(st[a][b])continue;
            if(g[a][b]==1)continue;
            st[a][b]=true;
            q.push({a,b});
            pre[a][b]=t;
        }
    }
    PII u={n-1,n-1};
    vector<PII>v;
    while(u.x!=0||u.y!=0)
    {
        v.push_back(u);
        auto t=pre[u.x][u.y];
        u=t;
    }
    cout<<0<<' '<<0<<endl;
    for(int i=v.size()-1;i>=0;i--)cout<<v[i].x<<' '<<v[i].y<<endl;
}
int main()
{
    cin>>n;
    for(int i=0;i<n;i++)
        for(int j=0;j<n;j++)
            cin>>g[i][j];
    bfs();
}

1100. 抓住那头牛

#include 
using namespace std;
const int N=1e5+10;
int dist[N];
bool st[N];
int n,k;
void bfs()
{
    memset(dist,0x3f,sizeof dist);
    queue<int>q;
    q.push(n);
    dist[n]=0;
    st[n]=true;
    while(q.size())
    {
        auto t=q.front();
        q.pop();
        if(t==k)break;
        int a=t-1,b=t+1,c=2*t;
        vector<int>v;
        v.push_back(a),v.push_back(b),v.push_back(c);
        for(int i=0;i<v.size();i++)
        {
            int x=v[i];
            if(x<0)continue;
            if(x>=N)continue;
            if(st[x])continue;
            st[x]=true;
            dist[x]=dist[t]+1;
            q.push(x);
        }
    }
    cout<<dist[k]<<endl;
}
int main()
{
    cin>>n>>k;
    bfs();
}

173. 矩阵距离(*)

#include 
#define x first
#define y second
using namespace std;
const int N=1010;
int dx[4]={-1,0,1,0};
int dy[4]={0,1,0,-1};
char g[N][N];
int n,m;
typedef pair<int,int>PII;
queue<PII>q;
int dist[N][N];
void bfs()
{
    memset(dist,0x3f,sizeof dist);
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<m;j++)
        {
            if(g[i][j]=='1')
            {
                q.push({i,j});
                dist[i][j]=0;
            }
        }
    }
    while(q.size())
    {
        auto t=q.front();
        q.pop();
        for(int i=0;i<4;i++)
        {
            int a=dx[i]+t.x,b=dy[i]+t.y;
            if(a<0||a>n||b<0||b>m)continue;
            if(dist[a][b]!=0x3f3f3f3f)continue;
            dist[a][b]=dist[t.x][t.y]+1;
            q.push({a,b});
        }
    }
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<m;j++)
        {
            cout<<dist[i][j]<<' ';
        }
        cout<<endl;
    }
}
int main()
{
    cin>>n>>m;
    for(int i=0;i<n;i++)
        for(int j=0;j<m;j++)
            cin>>g[i][j];
    bfs();
}

1107. 魔板

#include 
using namespace std;
char g[2][4];
unordered_map<string,pair<char,string>>pre;
unordered_map<string,int>dist;
void _set(string state)
{
    for(int i=0;i<4;i++)g[0][i]=state[i];
    for(int i=7,j=0;j<4;i--,j++)g[1][j]=state[i];
}
string get()
{
    string res;
    for(int i=0;i<4;i++)res+=g[0][i];
    for(int i=3;i>=0;i--)res+=g[1][i];
    return res;
}
string move0(string state)
{
    _set(state);
    for(int i=0;i<4;i++)swap(g[0][i],g[1][i]);
    return get();
}
string move1(string state)
{
    _set(state);
    char v0=g[0][3],v1=g[1][3];
    for(int i=3;i>=0;i--)
    {
        g[0][i]=g[0][i-1];
        g[1][i]=g[1][i-1];
    }
    g[0][0]=v0,g[1][0]=v1;
    return get();
}
string move2(string state)
{
    _set(state);
    int v=g[0][1];
    g[0][1]=g[1][1];
    g[1][1]=g[1][2];
    g[1][2]=g[0][2];
    g[0][2]=v;
    return get();
}
int bfs(string start, string ed)
{
    if(start==ed)return 0;
    queue<string>q;
    q.push(start);
    dist[start]=0;
    while(q.size())
    {
        auto t=q.front();
        q.pop();
        string m[3];
        m[0]=move0(t);
        m[1]=move1(t);
        m[2]=move2(t);
        for(int i=0;i<3;i++)
        {
            if(!dist.count(m[i]))
            {
                dist[m[i]]=dist[t]+1;
                pre[m[i]]={'A'+i,t};
                if(m[i]==ed)return dist[ed];
                q.push(m[i]);
            }
        }
    }
    return -1;
}
int main()
{
    int x;
    string start,ed;
    for(int i=0;i<8;i++)
    {
        cin>>x;
        ed+=char(x+'0');
    }
    for(int i=1;i<=8;i++)
    start+=char(i+'0');
    int step=bfs(start,ed);
    cout<<step<<endl;
    string res;
    while(ed!=start)
    {
        res+=pre[ed].first;
        ed=pre[ed].second;
    }
    reverse(res.begin(),res.end());
    if(step>0)cout<<res<<endl;
    return 0;
}

175. 电路维修(*)

#include 
#define x first
#define y second
using namespace std;
typedef pair<int,int>PII;
const int N=510,M=N*N;
int n,m;
char g[N][N];
int dist[N][N];
bool st[N][N];
char cs[]="\\/\\/";
int dx[4]={-1,-1,1,1},dy[4]={-1,1,1,-1};
int ix[4]={-1,-1,0,0},iy[4]={-1,0,0,-1};
int bfs()
{
    memset(dist,0x3f,sizeof dist);
    memset(st,false,sizeof st);
    dist[0][0]=0;
    deque<PII>q;
    q.push_back({0,0});
    while(q.size())
    {
        auto t=q.front();
        q.pop_front();
        if(st[t.x][t.y])continue;
        st[t.x][t.y]=true;
        for(int i=0;i<4;i++)
        {
            int a=dx[i]+t.x,b=dy[i]+t.y;
            if(a<0||a>n||b<0||b>m)continue;
            int ca=t.x+ix[i],cb=t.y+iy[i];
            int d=dist[t.x][t.y]+(g[ca][cb]!=cs[i]);
            if(d<dist[a][b])
            {
                dist[a][b]=d;
                if(g[ca][cb]!=cs[i])q.push_back({a,b});
                else q.push_front({a,b});
            }
        }
    }
    return dist[n][m];
}
int main()
{
    int t;
    cin>>t;
    while(t--)
    {
        cin>>n>>m;
        for(int i=0;i<n;i++)cin>>g[i];
        int t=bfs();
        if(t==0x3f3f3f3f)puts("NO SOLUTION");
        else cout<<t<<endl;
    }
    return 0;
}

1112. 迷宫

#include 
using namespace std;
const int N=110;
char g[N][N];
bool st[N][N];
int dx[4]={0,-1,0,1};
int dy[4]={-1,0,1,0};
int ax,ay,bx,by;
int n;
int t;
void dfs(int x,int y)
{
    st[x][y]=true;
    for(int i=0;i<4;i++)
    {
        int a=x+dx[i],b=y+dy[i];
        if(a<0||a>=n||b<0||b>=n)continue;
        if(g[a][b]=='#')continue;
        if(st[a][b])continue;
        dfs(a,b);
    }
}
void solve()
{
    memset(st,false,sizeof st);
    cin>>n;
    for(int i=0;i<n;i++)cin>>g[i];
    cin>>ax>>ay>>bx>>by;
    dfs(ax,ay);
    if(st[bx][by]&&g[ax][ay]!='#')puts("YES");
    else puts("NO");
}
int main()
{
    cin>>t;
    while(t--)solve();
    return 0;
}

1113. 红与黑

dfs

#include 
#define x first
#define y second
using namespace std;
typedef pair<int,int>PII;
int m,n;
const int N=31;
int dx[4]={0,-1,0,1};
int dy[4]={-1,0,1,0};
char g[N][N];
bool st[N][N];
PII start;
int res;
void dfs(PII t)
{
    res++;
    st[t.x][t.y]=true;
    for(int i=0;i<4;i++)
    {
        int a=dx[i]+t.x,b=dy[i]+t.y;
        if(a<0||a>=n||b<0||b>=m)continue;
        if(st[a][b])continue;
        if(g[a][b]=='#')continue;
        auto x=make_pair(a,b);
        dfs(x);
    }
}
int main()
{
    while(cin>>m>>n,m||n)
    {
        memset(st,false,sizeof st);
        for(int i=0;i<n;i++)
        {
            for(int j=0;j<m;j++)
            {
                cin>>g[i][j];
                if(g[i][j]=='@')start={i,j};
            }
        }
        res=0;
        dfs(start);
        cout<<res<<endl;
    }
}

4.11

1116. 马走日

#include 
using namespace std;
const int N=15;
int dx[8]={2,1,-1,-2,-2,-1,1,2};//方向数组
int dy[8]={1,2,2,1,-1,-2,-2,-1};
int g[N][N];
bool st[N][N];
int n,m;
int res;
int t;
void dfs(int x,int y,int depth)
{
    if(depth==n*m)
    {
        res++;
        return;
    }
    st[x][y]=true;
    for(int i=0;i<8;i++)
    {
        int a=dx[i]+x,b=dy[i]+y;
        if(a<0||a>=n||b<0||b>=m)continue;
        if(st[a][b])continue;
        dfs(a,b,depth+1);
    }
    st[x][y]=false;
}
void solve()
{
    cin>>n>>m;
    int x,y;
    cin>>x>>y;
    res=0;
    memset(st,false,sizeof st);
    dfs(x,y,1);
    cout<<res<<endl;
}
int main()
{
    cin>>t;
    while(t--)solve();
    return 0;
}

1117.单词接龙

#include 
using namespace std;
const int N = 21;
int n;
string word[N];
int g[N][N];
int used[N];
int res;
char start;
void dfs(string dragon, int last)
{
	res = max(res, (int)dragon.size());
	used[last]++;
	for (int i = 0; i < n; i++) 
	{
		if (g[last][i] && used[i] < 2)
		{
			dfs(dragon + word[i].substr(g[last][i]), i);
		}
	}
	used[last]--;
}
int main()
{
	cin >> n;
	for (int i = 0; i < n; i++)cin >> word[i];
	cin >> start;
	for (int i = 0; i < n; i++)
	{
		for (int j = 0; j < n; j++)
		{
			string a = word[i], b = word[j];
			for (int k = 1; k < min(a.size(), b.size()); k++)
			{
				if (a.substr(a.size() - k, k) == b.substr(0, k))
				{
					g[i][j] = k;
					break;
				}
			}
		}
	}
	for (int i = 0; i < n; i++)
	{
		if (start == word[i][0])
			dfs(word[i], i);
	}
	cout << res << endl;
	return 0;
}

1129. 热浪

#include 
#define x first
#define y second
using namespace std;
typedef pair<int,int>PII;
const int N=2510;
const int M=6200*2+10;
int h[N],e[M],ne[M],w[M],idx;
int n,m;
int start,ed;
int dist[N];
bool st[N];
void add(int a,int b,int c)
{
    e[idx]=b,ne[idx]=h[a],w[idx]=c,h[a]=idx++;
}
void dijkstra()
{
    memset(dist,0x3f,sizeof dist);
    dist[start]=0;
    priority_queue<PII,vector<PII>,greater<PII>>heap;
    heap.push({dist[start],start});
    while(heap.size())
    {
        auto t=heap.top();
        heap.pop();
        if(st[t.y])continue;
        st[t.y]=true;
        for(int i=h[t.y];~i;i=ne[i])
        {
            int j=e[i];
            if(dist[j]>dist[t.y]+w[i])
            {
                dist[j]=dist[t.y]+w[i];
                heap.push({dist[j],j});
            }
        }
    }
    cout<<dist[ed]<<endl;
}
int main()
{
    cin>>n>>m>>start>>ed;
    memset(h,-1,sizeof h);
    while(m--)
    {
        int a,b,c;
        cin>>a>>b>>c;
        add(a,b,c);
        add(b,a,c);
    }
    dijkstra();
    return 0;
}

1128.信使

#include 
using namespace std;
const int N=110;
const int M=410;
int g[N][N];
int n,m;
int dist[N];
bool st[N];
void dijkstra()
{
    memset(dist,0x3f,sizeof dist);
    dist[1]=0;
    for(int i=0;i<n;i++)
    {
        int t=-1;
        for(int j=1;j<=n;j++)
        {
            if(!st[j]&&(t==-1||dist[j]<dist[t]))
            {
                t=j;
            }
        }
        st[t]=true;
        for(int j=1;j<=n;j++)
        dist[j]=min(dist[j],dist[t]+g[t][j]);
    }
    int res=0;
    for(int i=1;i<=n;i++)
    {
        res=max(res,dist[i]);
    }
    if(res!=0x3f3f3f3f)
    cout<<res<<endl;
    else cout<<-1<<endl;
}
int main()
{
    cin>>n>>m;
    memset(g,0x3f,sizeof g);
    while(m--)
    {
        int a,b,c;
        cin>>a>>b>>c;
        g[a][b]=g[b][a]=c;
    }
    dijkstra();
    return 0;
}

1127. 香甜的奶油

#include 
using namespace std;
const int N=1010;
const int M=3010;
int h[N],e[M],ne[M],w[M],idx;
int dist[N];
int id[N];
bool st[N];
int n,m,p;
void add(int a,int b,int c)
{
    e[idx]=b,ne[idx]=h[a],w[idx]=c,h[a]=idx++;
}
int spfa(int start)
{
    memset(dist,0x3f,sizeof dist);
    memset(st,false,sizeof st);
    queue<int>q;
    q.push(start);
    st[start]=true;
    dist[start]=0;
    while(q.size())
    {
        auto t=q.front();
        q.pop();
        st[t]=false;
        for(int i=h[t];~i;i=ne[i])
        {
            int j=e[i];
            if(dist[j]>dist[t]+w[i])
            {
                dist[j]=dist[t]+w[i];
                if(!st[j])
                {
                    st[j]=true;
                    q.push(j);
                }
            }
        }
    }
    int res=0;
    for(int i=1;i<=n;i++)
    {
        res+=dist[id[i]];
        if(dist[i]==0x3f3f3f3f)return 0x3f3f3f3f;
    }
    return res;
}
int main()
{
    cin>>n>>p>>m;
    memset(h,-1,sizeof h);
    for(int i=1;i<=n;i++)cin>>id[i];
    while(m--)
    {
        int a,b,c;
        cin>>a>>b>>c;
        add(a,b,c);
        add(b,a,c);
    }
    int res=0x3f3f3f3f;
    for(int i=1;i<=p;i++)res=min(res,spfa(i));
    cout<<res<<endl;
    return 0;
}

1126. 最小花费

#include 
using namespace std;
const int N=2010;
double g[N][N];
double dist[N];
bool st[N];
int n,m;
int start,ed;
void dijkstra()
{
    dist[start]=1;
    for(int i=0;i<n;i++)
    {
        int t=-1;
        for(int j=1;j<=n;j++)
        {
            if(!st[j]&&(t==-1||dist[t]<dist[j]))
            {
                t=j;
            }
        }
        st[t]=true;
        for(int j=1;j<=n;j++)
        {
            dist[j]=max(dist[j],dist[t]*g[t][j]);
        }
    }
    printf("%.8f",100/dist[ed]);
}
int main()
{
    cin>>n>>m;
    while(m--)
    {
        int a,b,c;
        cin>>a>>b>>c;
        double z=(100-c)*1.0/100;
        g[a][b]=g[b][a]=max(g[a][b],z);
    }
    cin>>start>>ed;
    dijkstra();
    return 0;
}

920. 最优乘车(*)

#include 
using namespace std;
const int N=510;
bool g[N][N];
int n,m;
int dist[N];
bool st[N];
int stop[N];
void bfs()
{
    memset(dist,0x3f,sizeof dist);
    queue<int>q;
    q.push(1);
    st[1]=true;
    dist[1]=0;
    while(q.size())
    {
        auto t=q.front();
        q.pop();
        for(int i=1;i<=n;i++)
        {
            if(g[t][i])
            {
                if(st[i])continue;
                st[i]=true;
                q.push(i);
                dist[i]=dist[t]+1;
            }
        }
    }
    if(dist[n]==0x3f3f3f3f)puts("NO");
    else cout<<max(dist[n]-1,0)<<endl;
}
int main()
{
    cin>>m>>n;
    string line;
    getchar();
    while(m--)
    {
        getline(cin,line);
        stringstream ssin(line);
        int cnt=0,p;
        while(ssin>>p)stop[cnt++]=p;
        for(int i=0;i<cnt;i++)
        {
            for(int j=i+1;j<cnt;j++)
            {
                g[stop[i]][stop[j]]=true;
            }
        }
    }
    bfs();
    return 0;
}

903. 昂贵的聘礼

#include 
using namespace std;
const int N=110;
int w[N][N];
int level[N];
bool st[N];
int dist[N];
int m,n;
int dijkstra(int down,int up)
{
    memset(dist,0x3f,sizeof dist);
    memset(st,false,sizeof st);
    dist[0]=0;
    for(int i=1;i<=n+1;i++)
    {
        int t=-1;
        for(int j=0;j<=n;j++)
        {
            if(!st[j]&&(t==-1||dist[j]<dist[t]))
            t=j;
        }
        st[t]=true;
        for(int j=0;j<=n;j++)
        {
            if(level[j]>=down&&level[j]<=up)
            {
                dist[j]=min(dist[j],dist[t]+w[t][j]);
            }
        }
    }
    return dist[1];
}
int main()
{
    cin>>m>>n;
    memset(w,0x3f,sizeof w);
    for(int i=1;i<=n;i++)
    {
        int price,cnt;
        cin>>price>>level[i]>>cnt;
        w[0][i]=min(price,w[0][i]);
        while(cnt--)
        {
            int id,cost;
            cin>>id>>cost;
            w[id][i]=min(w[id][i],cost);
        }
    }
    int res=0x3f3f3f3f;
    for(int i=level[1]-m;i<=level[1];i++)
    {
        res=min(res,dijkstra(i,i+m));
    }
    cout<<res<<endl;
    return 0;
}

1118. 分成互质组

#include 
using namespace std;
const int N=15;
int n;
int a[N];
vector<int>g[N];
int cnt,res=N;
int gcd(int a,int b)
{
    return b?gcd(b,a%b):a;
}
bool check(int u,int c)
{
    for(int i=0;i<g[c].size();i++)
    {
        if(gcd(u,g[c][i])>1)return false;
    }
    return true;
}
void dfs(int u)
{
    if(u==n)
    {
        res=min(res,cnt);
        return;
    }
    for(int i=0;i<cnt;i++)
    {
        if(check(a[u],i))
        {
            g[i].push_back(a[u]);
            dfs(u+1);
            g[i].pop_back();
        }
    }
    g[cnt++].push_back(a[u]);
    dfs(u+1);
    g[--cnt].pop_back();
}
int main()
{
    cin>>n;
    for(int i=0;i<n;i++)cin>>a[i];
    dfs(0);
    cout<<res<<endl;
    return 0;
}

165. 小猫爬山

#include 
using namespace std;
const int N=20;
int n,m;
int w[N];
int sum[N];
int ans=N;
void dfs(int u,int k)
{
    if(k>=ans)return;
    if(u==n)
    {
        ans=k;
        return;
    }
    for(int i=0;i<k;i++)
    {
        if(sum[i]+w[u]<=m)
        {
            sum[i]+=w[u];
            dfs(u+1,k);
            sum[i]-=w[u];
        }
    }
    sum[k]=w[u];
    dfs(u+1,k+1);
    sum[k]=0;
}
int main()
{
    cin>>n>>m;
    for(int i=0;i<n;i++)cin>>w[i];
    sort(w,w+n,greater<int>());
    dfs(0,0);
    cout<<ans<<endl;
    return 0;
}

4.12

1135. 新年好

#include 
#define x first
#define y second
using namespace std;
typedef pair<int,int>PII;
const int N=50010;
const int M=2e5+10;
int h[N],e[M],ne[M],w[M],idx;
int n,m;
bool st[N];
int dist[6][N];
int source[6];
void add(int a,int b,int c)
{
    e[idx]=b,w[idx]=c,ne[idx]=h[a],h[a]=idx++;
}
int dfs(int u,int start,int distance)
{
    if(u==6)return distance;
    int res=0x3f3f3f3f;
    st[start]=true;
    for(int i=1;i<=5;i++)
    {
        int next=source[i];
        if(!st[i]&&dist[start][next]!=0x3f3f3f3f)
        {
            res=min(res,dfs(u+1,i,distance+dist[start][next]));
        }
    }
    st[start]=false;
    return res;
}
void dijkstra(int start,int dist[])
{
    memset(dist,0x3f,4*N);
    memset(st,false, sizeof st);
    priority_queue<PII,vector<PII>,greater<PII>>heap;
    dist[start]=0;
    heap.push({dist[start],start});
    while(heap.size())
    {
        auto t=heap.top();
        heap.pop();
        if(st[t.y])continue;
        st[t.y]=true;
        for(int i=h[t.y];~i;i=ne[i])
        {
            int j=e[i];
            if(dist[j]>dist[t.y]+w[i])
            {
                dist[j]=dist[t.y]+w[i];
                heap.push({dist[j],j});
            }
        }
    }
}
int main()
{
    memset(h,-1,sizeof h);
    cin>>n>>m;
    for(int i=1;i<=5;i++)cin>>source[i];
    source[0]=1;
    while(m--)
    {
        int a,b,c;
        cin>>a>>b>>c;
        add(a,b,c);
        add(b,a,c);
    }
    for(int i=0;i<6;i++)dijkstra(source[i],dist[i]);
    memset(st,false,sizeof st);
    cout<<dfs(1,0,0)<<endl;
    return 0;
}

340. 通信线路

#include 
using namespace std;
const int N=1010;
const int M=20010;
int h[N],e[M],ne[M],w[M],idx;
bool st[N];
int dist[N];
int n,m,k;
void add(int a,int b,int c)
{
    e[idx]=b,ne[idx]=h[a],w[idx]=c,h[a]=idx++;
}
bool check(int bound)
{
    memset(dist,0x3f,sizeof dist);
    memset(st,false ,sizeof st);
    dist[1]=0;
    deque<int>q;
    q.push_back(1);
    while(q.size())
    {
        auto t=q.front();
        q.pop_front();
        if(st[t])continue;
        st[t]=true;
        for(int i=h[t];~i;i=ne[i])
        {
            int j=e[i];
            int x=w[i]>bound;
            if(dist[j]>dist[t]+x)
            {
                dist[j]=dist[t]+x;
                if(x)q.push_back(j);
                else q.push_front(j);
            }
        }
    }
    return dist[n]<=k;
}
int main()
{
    cin>>n>>m>>k;
    memset(h,-1,sizeof h);
    while(m--)
    {
        int a,b,c;
        cin>>a>>b>>c;
        add(a,b,c);
        add(b,a,c);
    }
    int l=0,r=1e6+10;
    while(l<r)
    {
        int mid=l+r>>1;
        if(check(mid))r=mid;
        else l=mid+1;
    }
    if(r==1e6+10)cout<<-1<<endl;
    else cout<<r<<endl;
    return 0;
}

341. 最优贸易(*)

#include 
using namespace std;
const int N=100010,M=2000010;
int n,m;
int price[N];
int h[N],rh[N],e[M],ne[M],idx;
int dmin[N],dmax[N];
bool st[N];
void add(int *h,int a,int b)
{
    e[idx]=b,ne[idx]=h[a],h[a]=idx++;
}
void spfa(int *dist,int start,int *h,bool f)
{
    queue<int>q;
    memset(st,false,sizeof st);
    if(f)memset(dist,0x3f,4*N);
    q.push(start);
    st[start]=true;
    dist[start]=price[start];
    while(q.size())
    {
        auto t=q.front();
        q.pop();
        st[t]=false;
        for(int i=h[t];~i;i=ne[i])
        {
            int j=e[i];
            if(f&&dist[j]>min(dist[t],price[j])||!f&&dist[j]<max(dist[t],price[j]))
            {
                if(f)dist[j]=min(dist[t],price[j]);
                else dist[j]=max(dist[t],price[j]);
                if(st[j])continue;
                st[j]=true;
                q.push(j);
            }
        }
    }
}
int main()
{
    cin>>n>>m;
    memset(h,-1,sizeof h);
    memset(rh,-1,sizeof rh);
    for(int i=1;i<=n;i++)cin>>price[i];
    while(m--)
    {
        int a,b,c;
        cin>>a>>b>>c;
        add(h,a,b);
        add(rh,b,a);
        if(c==2)add(h,b,a),add(rh,a,b);
    }
    spfa(dmin,1,h,true);
    spfa(dmax,n,rh,false);
    int res=0;
    for(int i=1;i<=n;i++)res=max(res,dmax[i]-dmin[i]);
    cout<<res<<endl;
    return 0;
}

1137. 选择最佳路线

#include 
using namespace std;
const int N=1010;
const int M=40010;
int h[N],e[M],ne[M],w[M],idx;
int n,m,s;
bool st[N];
int dist[N];
void add(int a,int b,int c)
{
    e[idx]=b,ne[idx]=h[a],w[idx]=c,h[a]=idx++;
}
int spfa()
{
    memset(st,false,sizeof st);
    memset(dist,0x3f,sizeof dist);
    queue<int>q;
    dist[0]=0;
    q.push(0);
    st[0]=true;
    while(q.size())
    {
        auto t=q.front();
        q.pop();
        st[t]=false;
        for(int i=h[t];~i;i=ne[i])
        {
            int j=e[i];
            if(dist[j]>dist[t]+w[i])
            {
                dist[j]=dist[t]+w[i];
                if(st[j])continue;
                st[j]=true;
                q.push(j);
            }
        }
    }
    return dist[s];
}
int main()
{
    while(cin>>n>>m>>s)
    {
        memset(h,-1,sizeof h);
        idx=0;
        while(m--)
        {
            int a,b,c;
            cin>>a>>b>>c;
            add(a,b,c);
        }
        int k;
        cin>>k;
        for(int i=0;i<k;i++)
        {
            int x;
            cin>>x;
            add(0,x,0);
        }
        if(spfa()!=0x3f3f3f3f)cout<<dist[s]<<endl;
        else puts("-1");
    }
    return 0;
}

1134. 最短路计数

#include 
using namespace std;
const int N=1e5+10;
const int M=4e5+10;
const int mod=100003;
int h[N],e[M],ne[M],idx;
int cnt[N];
int dist[N];
int n,m;
bool st[N];
void add(int a,int b)
{
    e[idx]=b,ne[idx]=h[a],h[a]=idx++;
}
void bfs()
{
    memset(dist,0x3f,sizeof dist);
    cnt[1]=1;
    queue<int>q;
    q.push(1);
    dist[1]=0;
    while(q.size())
    {
        auto t=q.front();
        q.pop();
        if(st[t])continue;
        st[t]=true;
        for(int i=h[t];~i;i=ne[i])
        {
            int j=e[i];
            if(dist[j]>dist[t]+1)
            {
                dist[j]=dist[t]+1;
                cnt[j]=cnt[t]%mod;
                q.push(j);
            }
            else if(dist[j]==dist[t]+1)
            {
                cnt[j]=(cnt[t]+cnt[j])%mod;
            }
        }
    }
    for(int i=1;i<=n;i++)cout<<cnt[i]<<endl;
}
int main()
{
    cin>>n>>m;
    memset(h,-1,sizeof h);
    while(m--)
    {
        int a,b;
        cin>>a>>b;
        add(a,b);
        add(b,a);
    }
    bfs();
    return 0;
}

4.13

342. 道路与航线

#include 
#define x first
#define y second
using namespace std;
const int N=25010,M=150010;
typedef pair<int,int>PII;
int h[N],e[M],ne[M],w[M],idx;
int dist[N];
bool st[N];
int n,mr,mp,s;
int id[N],bcnt;
int deg[N];
queue<int>q;
vector<int>block[N];
void add(int a,int b,int c)
{
    e[idx]=b,w[idx]=c,ne[idx]=h[a],h[a]=idx++;
}
void dfs(int u)
{
    block[bcnt].push_back(u);
    id[u]=bcnt;
    for(int i=h[u];~i;i=ne[i])
    {
        int j=e[i];
        if(!id[j])dfs(j);
    }
}
void dijkstra(int block_id)
{
    priority_queue<PII,vector<PII>,greater<PII>>heap;
    for(auto u:block[block_id])heap.push({dist[u],u});
    while(heap.size())
    {
        auto t=heap.top();
        heap.pop();
        if(st[t.y])continue;
        st[t.y]=true;
        for(int i=h[t.y];~i;i=ne[i])
        {
            int j=e[i];
            if(dist[j]>dist[t.y]+w[i])
            {
                dist[j]=dist[t.y]+w[i];
                if(id[j]==block_id)heap.push({dist[j],j});
            }
            if(id[j]!=block_id&&--deg[id[j]]==0)q.push(id[j]);
        }
    }
}
void topsort()
{
    memset(dist,0x3f,sizeof dist);
    dist[s]=0;
    for(int i=1;i<=bcnt;i++)
    {
        if(!deg[i])q.push(i);
    }
    while(q.size())
    {
        auto t=q.front();
        q.pop();
        dijkstra(t);
    }
}
int main()
{
    cin>>n>>mr>>mp>>s;
    memset(h,-1,sizeof h);
    for(int i=0;i<mr;i++)
    {
        int a,b,c;
        cin>>a>>b>>c;
        add(a,b,c);
        add(b,a,c);
    }
    for(int i=1;i<=n;i++)
    {
        if(!id[i])
        {
            bcnt++;
            dfs(i);
        }
    }
    for(int i=0;i<mp;i++)
    {
        int a,b,c;
        cin>>a>>b>>c;
        add(a,b,c);
        deg[id[b]]++;
    }
    topsort();
    for(int i=1;i<=n;i++)
    {
        if(dist[i]>0x3f3f3f3f/2)puts("NO PATH");
        else cout<<dist[i]<<endl;
    }
    return 0;
}

383. 观光(*)

#include 
using namespace std;
const int N=1010,M=10010;
int h[N],e[M],ne[M],w[M],idx;
int cnt[N][2];
int dist[N][2];
bool st[N][2];
int n,m,s,t;
struct node
{
    int id,type,distance;
    bool operator>(const node&a)const
    {
        return distance>a.distance;
    }
};
void add(int a,int b,int c)
{
    e[idx]=b,ne[idx]=h[a],w[idx]=c,h[a]=idx++;
}
int dijkstra()
{
    memset(st,false,sizeof st);
    memset(dist,0x3f,sizeof dist);
    memset(cnt,0,sizeof cnt);
    priority_queue<node,vector<node>,greater<node>>heap;
    heap.push({s,0,0});
    dist[s][0]=0;
    cnt[s][0]=1;
    while(heap.size())
    {
        auto t=heap.top();
        heap.pop();
        int ver=t.id,type=t.type,distance=t.distance;
        if(st[ver][type])continue;
        st[ver][type]=true;
        for(int i=h[ver];~i;i=ne[i])
        {
            int j=e[i];
            if(dist[j][0]>dist[ver][type]+w[i])
            {
                dist[j][1]=dist[j][0];
                cnt[j][1]=cnt[j][0];
                heap.push({j,1,dist[j][1]});
                dist[j][0]=dist[ver][type]+w[i];
                cnt[j][0]=cnt[ver][type];
                heap.push({j,0,dist[j][0]});
            }
            else if(dist[j][0]==dist[ver][type]+w[i])
            {
                cnt[j][0]+=cnt[ver][type];
            }
            else if(dist[j][1]>dist[ver][type]+w[i])
            {
                dist[j][1]=dist[ver][type]+w[i];
                cnt[j][1]=cnt[ver][type];
                heap.push({j,1,dist[j][1]});
            }
            else if(dist[j][1]==dist[ver][type]+w[i])
            {
                cnt[j][1]+=cnt[ver][type];
            }
        }
    }
    int res=cnt[t][0];
    if(dist[t][0]+1==dist[t][1])res+=cnt[t][1];
    return res;
}
int main()
{
    int _;
    cin>>_;
    while(_--)
    {
        memset(h,-1,sizeof h);
        cin>>n>>m;
        for(int i=0;i<m;i++)
        {
            int a,b,c;
            cin>>a>>b>>c;
            add(a,b,c);
        }
        cin>>s>>t;
        cout<<dijkstra()<<endl;
    }
    return 0;
}

1125. 牛的旅行

#include 
#define x first
#define y second
using namespace std;
typedef pair<double,double>PDD;
const int N=155;
const double INF=1e20;
int n;
PDD q[N];
double d[N][N];
double maxd[N];
char g[N][N];
double get_dist(PDD a, PDD b)
{
    double dx=a.x-b.x;
    double dy=a.y-b.y;
    return sqrt(dx*dx+dy*dy);
}
int main()
{
    cin>>n;
    for(int i=0;i<n;i++)cin>>q[i].x>>q[i].y;
    for(int i=0;i<n;i++)cin>>g[i];
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<n;j++)
        {
            if(i==j)d[i][j]=0;
            else if(g[i][j]=='1')d[i][j]=get_dist(q[i],q[j]);
            else d[i][j]=INF;
        }
    }
    for(int k=0;k<n;k++)
    {
        for(int i=0;i<n;i++)
        {
            for(int j=0;j<n;j++)
            {
                d[i][j]=min(d[i][j],d[i][k]+d[k][j]);
            }
        }
    }
    double r1=0;
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<n;j++)
        {
            if(d[i][j]<INF/2)maxd[i]=max(maxd[i],d[i][j]);
        }
        r1=max(r1,maxd[i]);
    }
    double r2=INF;
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<n;j++)
        {
            if(d[i][j]>INF/2)r2=min(r2,maxd[i]+maxd[j]+get_dist(q[i],q[j]));
        }
    }
    printf("%.6f",max(r1,r2));
    return 0;
}

1140. 最短网络

#include 
using namespace std;
const int N=110;
int n;
int w[N][N];
int dist[N];
bool st[N];
int prim()
{
    memset(dist,0x3f,sizeof dist);
    dist[1]=0;
    int res=0;
    for(int i=1;i<=n;i++)
    {
        int t=-1;
        for(int j=1;j<=n;j++)
        {
            if(!st[j]&&(t==-1||dist[j]<dist[t]))
            t=j;
        }
        st[t]=true;
        res+=dist[t];
        for(int j=1;j<=n;j++)
        {
            dist[j]=min(dist[j],w[t][j]);
        }
    }
    return res;
}
int main()
{
    cin>>n;
    memset(w,0x3f,sizeof w);
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=n;j++)
        {
            cin>>w[i][j];
        }
    }
    cout<<prim()<<endl;
    return 0;
}

1141. 局域网

#include 
using namespace std;
const int N=110,M=210;
struct node
{
    int a,b,w;
    bool operator<(const node &t)const
    {
        return w<t.w;
    }
}e[M];
int f[N];
int n,m;
int find(int x)
{
    if(x!=f[x])f[x]=find(f[x]);
    return f[x];
}
void unite(int x,int y)
{
    int a=find(x);
    int b=find(y);
    if(a!=b)f[b]=a;
}
int main()
{
    cin>>n>>m;
    for(int i=0;i<N;i++)f[i]=i;
    for(int i=0;i<m;i++)cin>>e[i].a>>e[i].b>>e[i].w;
    sort(e,e+m);
    int res=0;
    for(int i=0;i<m;i++)
    {
        int a=e[i].a,b=e[i].b,w=e[i].w;
        if(find(a)!=find(b))unite(a,b);
        else res+=w;
    }
    cout<<res<<endl;
    return 0;
}

1142. 繁忙的都市

#include 
using namespace std;
const int N=310,M=8010;
struct node
{
    int a,b,w;
    bool operator<(const node &t)const
    {
        return w<t.w;
    }
}e[M];
int n,m;
int f[N];
int find(int x)
{
    if(x!=f[x])f[x]=find(f[x]);
    return f[x];
}
void unite(int a,int b)
{
    int x=find(a);
    int y=find(b);
    if(x!=y)f[y]=x;
}
int main()
{
    cin>>n>>m;
    for(int i=0;i<N;i++)f[i]=i;
    for(int i=0;i<m;i++)cin>>e[i].a>>e[i].b>>e[i].w;
    sort(e,e+m);
    int res=0;
    for(int i=0;i<m;i++)
    {
        int a=e[i].a,b=e[i].b,w=e[i].w;
        if(find(a)!=find(b))
        {
            unite(a,b);
            res=w;
        }
    }
    cout<<n-1<<' '<<res<<endl;
    return 0;
}

1143. 联络员

#include 
using namespace std;
const int N=2010;
const int M=10010;
int n,m;
int f[N];
struct node
{
    int a,b,w;
    bool operator<(const node &t)const
    {
        return w<t.w;
    }
}e[M];
int find(int x)
{
    if(x!=f[x])f[x]=find(f[x]);
    return f[x];
}
void unite(int a,int b)
{
    int x=find(a);
    int y=find(b);
    if(x!=y)f[y]=x;
}
int main()
{
    cin>>n>>m;
    int res=0;
    for(int i=0;i<N;i++)f[i]=i;
    int k=0;
    for(int i=0;i<m;i++)
    {
        int t,a,b,c;
        cin>>t>>a>>b>>c;
        if(t==1)
        {
            if(find(a)!=find(b))
            unite(a,b);
            res+=c;
        }
        else e[k++]={a,b,c};
    }
    sort(e,e+k);
    for(int i=0;i<k;i++)
    {
        int a=e[i].a,b=e[i].b,w=e[i].w;
        if(find(a)!=find(b))
        {
            unite(a,b);
            res+=w;
        }
    }
    cout<<res<<endl;
    return 0;
}

1146. 新的开始

#include 
using namespace std;
const int N=310;
int w[N][N];
int dist[N];
bool st[N];
int n;
void prim()
{
    memset(dist,0x3f,sizeof dist);
    dist[1]=0;
    int res=0;
    for(int i=0;i<=n;i++)
    {
        int t=-1;
        for(int j=0;j<=n;j++)
        {
            if(!st[j]&&(t==-1||dist[j]<dist[t]))
            {
                t=j;
            }
        }
        st[t]=true;
        res+=dist[t];
        for(int j=0;j<=n;j++)
        {
            dist[j]=min(dist[j],w[t][j]);
        }
    }
    cout<<res<<endl;
}
int main()
{
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        int x;
        cin>>x;
        w[i][0]=w[0][i]=x;
    }
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=n;j++)
        {
            cin>>w[i][j];
        }
    }
    prim();
    return 0;
}

904 . 虫洞

#include 
using namespace std;
const int N=510;
const int M=5210;
int n,m1,m2;
int h[N],e[M],ne[M],w[M],idx;
int dist[N];
int cnt[N];
bool st[N];
void add(int a,int b,int c)
{
    e[idx]=b,ne[idx]=h[a],w[idx]=c,h[a]=idx++;
}
bool spfa()
{
    memset(dist,0x3f,sizeof dist);
    memset(st,false ,sizeof st);
    memset(cnt,0,sizeof cnt);
    queue<int>q;
    for(int i=1;i<=n;i++)
    {
        q.push(i);
        st[i]=true;
    }
    while(q.size())
    {
        auto t=q.front();
        q.pop();
        st[t]=false;
        for(int i=h[t];~i;i=ne[i])
        {
            int j=e[i];
            if(dist[j]>dist[t]+w[i])
            {
                dist[j]=dist[t]+w[i];
                cnt[j]=cnt[t]+1;
                if(cnt[j]>=n)return true;
                if(!st[j])
                {
                    st[j]=true;
                    q.push(j);
                }
            }
        }
    }
    return false;
}
int main()
{
    int _;
    cin>>_;
    while(_--)
    {
        cin>>n>>m1>>m2;
        memset(h,-1,sizeof h);
        idx=0;
        for(int i=0;i<m1;i++)
        {
            int a,b,c;
            cin>>a>>b>>c;
            add(a,b,c),add(b,a,c);
        }
        for(int i=0;i<m2;i++)
        {
            int a,b,c;
            cin>>a>>b>>c;
            add(a,b,-c);
        }
        if(spfa())cout<<"YES"<<endl;
        else cout<<"NO"<<endl;
    }
    return 0;
}

1191. 家谱树

#include 
using namespace std;
const int N=110;
const int M=N*N;
int h[N],e[M],ne[M],idx;
int ind[N];
int n;
void add(int a,int b)
{
    e[idx]=b,ne[idx]=h[a],h[a]=idx++;
}
void topsort()
{
    queue<int>q;
    for(int i=1;i<=n;i++)
    {
        if(!ind[i])
        {
            q.push(i);
        }
    }
    while(q.size())
    {
        auto t=q.front();
        q.pop();
        cout<<t<<' ';
        for(int i=h[t];~i;i=ne[i])
        {
            int j=e[i];
            if(--ind[j]==0)
            {
                q.push(j);
            }
        }
    }
}
int main()
{
    cin>>n;
    memset(h,-1,sizeof h);
    for(int i=1;i<=n;i++)
    {
        int son;
        while(cin>>son,son)
        {
            add(i,son);
            ind[son]++;
        }
    }
    topsort();
    return 0;
}

4.14

1145. 北极通讯网络

#include 
#define x first
#define y second
using namespace std;
typedef pair<int,int>PII;
const int N=510;
const int M=N*N/2;
struct node 
{
    int a,b;
    double w;
    bool operator<(const node &t)const
    {
        return w<t.w;
    }
}e[M];
int f[N];
int n,k;
PII p[N];
int find(int x)
{
    if(x!=f[x])f[x]=find(f[x]);
    return f[x];
}
double get_dist(PII a,PII b)
{
    return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
}
int main()
{
    cin>>n>>k;
    for(int i=0;i<n;i++)cin>>p[i].x>>p[i].y;
    int m=0;
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<i;j++)
        {
            e[m++]={i,j,get_dist(p[i],p[j])};
        }
    }
    sort(e,e+m);
    for(int i=0;i<N;i++)f[i]=i;
    int cnt=n;
    double res=0;
    for(int i=0;i<m;i++)
    {
        if(cnt<=k)break;
        int a=e[i].a,b=e[i].b;
        double w=e[i].w;
        if(find(a)!=find(b))
        {
            f[find(b)]=find(a);
            cnt--;
            res=w;
        }
    }
    printf("%.2f",res);
    return 0;
}

346. 走廊泼水节

#include 
using namespace std;
const int N=6010;
struct node
{
    int a,b,w;
    bool operator<(const node &t)const
    {
        return w<t.w;
    }
}e[N];
int f[N];
int cnt[N];
int n;
int find(int x)
{
    if(x!=f[x])f[x]=find(f[x]);
    return f[x];
}
int main()
{
    int t;
    cin>>t;
    while(t--)
    {
        cin>>n;
        for(int i=0;i<N;i++)f[i]=i,cnt[i]=1;
        for(int i=0;i<n-1;i++)cin>>e[i].a>>e[i].b>>e[i].w;
        sort(e,e+n-1);
        int res=0;
        for(int i=0;i<n-1;i++)
        {
            int a=find(e[i].a),b=find(e[i].b),w=e[i].w;
            if(a!=b)
            {
                res+=(cnt[a]*cnt[b]-1)*(w+1);
                f[b]=a;
                cnt[a]+=cnt[b];
            }
        }
        cout<<res<<endl;
    }
    return 0;
}

361. 观光奶牛(*)

#include 
using namespace std;
const int N=1010,M=5010;
const double eps=1e-4;
int n,m;
int w_ver[N];
int h[N],e[M],ne[M],w_edg[M],idx;
double dist[N];
int cnt[N];
bool st[N];
void add(int a,int b,int c)
{
    e[idx]=b,ne[idx]=h[a],w_edg[idx]=c,h[a]=idx++;
}
bool check(double limit)
{
    memset(dist,0,sizeof dist);
    memset(cnt,0,sizeof cnt);
    memset(st,0,sizeof st);
    queue<int>q;
    for(int i=1;i<=n;i++)
    {
        q.push(i);
        st[i]=true;
    }
    while(q.size())
    {
        auto t=q.front();
        q.pop();
        st[t]=false;
        for(int i=h[t];~i;i=ne[i])
        {
            int j=e[i];
            if(dist[j]<dist[t]+w_ver[t]-w_edg[i]*limit)
            {
                dist[j]=dist[t]+w_ver[t]-w_edg[i]*limit;
                cnt[j]=cnt[t]+1;
                if(cnt[j]>=n)return true;
                if(!st[j])
                {
                    q.push(j);
                    st[j]=true;
                }
            }
        }
    }
    return false;
}
int main()
{
    cin>>n>>m;
    for(int i=1;i<=n;i++)cin>>w_ver[i];
    memset(h,-1,sizeof h);
    while(m--)
    {
        int a,b,c;
        cin>>a>>b>>c;
        add(a,b,c);
    }
    double l=1,r=1000;
    while(r-l>eps)
    {
        double mid=(l+r)/2;
        if(check(mid))l=mid;
        else r=mid;
    }
    printf("%.2f",r);
    return 0;
}

1172.祖孙询问

#include 
using namespace std;
const int N=40010,M=N*2;
int n,m;
int h[N],e[M],ne[M],idx;
int depth[N],fa[N][16];
void add(int a,int b)
{
    e[idx]=b,ne[idx]=h[a],h[a]=idx++;
}
void bfs(int root)
{
    memset(depth,0x3f,sizeof depth);
    depth[0]=0,depth[root]=1;//哨兵,防止跳过根节点
    queue<int>q;
    q.push(root);
    while(q.size())
    {
        auto t=q.front();
        q.pop();
        for(int i=h[t];~i;i=ne[i])
        {
            int j=e[i];
            if(depth[j]>depth[t]+1)//j还没有被搜索过
            {
                depth[j]=depth[t]+1;
                q.push(j);
                fa[j][0]=t;//j向上跳2^0为t
                for(int k=1;k<=15;k++)
                fa[j][k]=fa[fa[j][k-1]][k-1];//2^j= 2^j-1 + 2^j-1
            }
        }
    }
}
int lca(int a,int b)
{
    if(depth[a]<depth[b])swap(a,b);
    for(int k=15;k>=0;k--)
    {
        if(depth[fa[a][k]]>=depth[b])
        {
            a=fa[a][k];
        }
    }
    if(a==b)return a;
    for(int k=15;k>=0;k--)
    {
        if(fa[a][k]!=fa[b][k])
        {
            a=fa[a][k];
            b=fa[b][k];
        }
    }
    return fa[a][0];
}
int main()
{
    cin>>n;
    int root=0;
    memset(h,-1,sizeof h);
    for(int i=0;i<n;i++)
    {
        int a,b;
        cin>>a>>b;
        if(b==-1)root=a;
        else add(a,b),add(b,a);
    }
    bfs(root);
    cin>>m;
    while(m--)
    {
        int a,b;
        cin>>a>>b;
        int p=lca(a,b);
        if(p==a)puts("1");
        else if(p==b)puts("2");
        else puts("0");
    }
    return 0;
}

1171. 距离(*)

#include 
using namespace std;
typedef pair<int,int>PII;
const int N=10010,M=N*2;
int n,m;
int h[N],e[M],ne[M],w[M],idx;
int dist[N];
int p[N];
int res[M];
int st[N];
vector<PII>query[N];
void add(int a,int b,int c)
{
    e[idx]=b,ne[idx]=h[a],w[idx]=c,h[a]=idx++;
}
void dfs(int u,int fa)
{
    for(int i=h[u];~i;i=ne[i])
    {
        int j=e[i];
        if(j==fa)continue;
        dist[j]=dist[u]+w[i];
        dfs(j,u);
    }
}
int find(int x)
{
    if(p[x]!=x)p[x]=find(p[x]);
    return p[x];
}
void tarjan(int u)
{
    st[u]=1;
    for(int i=h[u];~i;i=ne[i])
    {
        int j=e[i];
        if(!st[j])
        {
            tarjan(j);
            p[j]=u;
        }
    }
    for(auto t:query[u])
    {
        int y=t.first,id=t.second;
        if(st[y]==2)
        {
            int anc=find(y);
            res[id]=dist[u]+dist[y]-dist[anc]*2;
        }
    }
    st[u]=2;
}
int main()
{
    cin>>n>>m;
    memset(h,-1,sizeof h);
    for(int i=0;i<n-1;i++)
    {
        int a,b,c;
        cin>>a>>b>>c;
        add(a,b,c);
        add(b,a,c);
    }
    for(int i=0;i<m;i++)
    {
        int a,b;
        cin>>a>>b;
        if(a!=b)
        {
            query[a].push_back({b,i});
            query[b].push_back({a,i});
        }
    }
    for(int i=1;i<=n;i++)p[i]=i;
    dfs(1,-1);
    tarjan(1);
    for(int i=0;i<m;i++)
        cout<<res[i]<<endl;
    return 0;
}

257.关押罪犯

#include 
using namespace std;
const int N=20010,M=200010;
int n,m;
int h[N],e[M],ne[M],w[M],idx;
int color[N];
void add(int a,int b,int c)
{
    e[idx]=b,ne[idx]=h[a],w[idx]=c,h[a]=idx++;
}
bool dfs(int u,int c,int limit)
{
    color[u]=c;
    for(int i=h[u];~i;i=ne[i])
    {
        int j=e[i];
        if(w[i]<=limit)continue;
        if(color[j])
        {
            if(color[j]==c)return false;
        }
        else if(!dfs(j,3-c,limit))return false;
    }
    return true;
}
bool check(int limit)
{
    memset(color,0,sizeof color);
    for(int i=1;i<=n;i++)
    {
        if(color[i]==0)
        {
            if(!dfs(i,1,limit))return false;
        }
    }
    return true;
}
int main()
{
    cin>>n>>m;
    memset(h,-1,sizeof h);
    while(m--)
    {
        int a,b,c;
        cin>>a>>b>>c;
        add(a,b,c);
        add(b,a,c);
    }
    int l=0,r=1e9;
    while(l<r)
    {
        int mid=l+r>>1;
        if(check(mid))r=mid;
        else l=mid+1;
    }
    cout<<l<<endl;
    return 0;
}

372. 棋盘覆盖(*)

#include 
using namespace std;
#define x first
#define y second
typedef pair<int,int>PII;
const int N=110;
int n,m;
PII match[N][N];
bool g[N][N],st[N][N];
int dx[4]={-1,0,1,0};
int dy[4]={0,1,0,-1};
bool find(int x,int y)
{
    for(int i=0;i<4;i++)
    {
        int a=x+dx[i];
        int b=y+dy[i];
        if(a>0&&a<=n&&b>0&&b<=n&&!g[a][b]&&!st[a][b])
        {
            st[a][b]=true;
            auto t=match[a][b];
            if(t.x==-1||find(t.x,t.y))
            {
                match[a][b]={x,y};
                return true;
            }
        }
    }
    return false;
}
int main()
{
    cin>>n>>m;
    while(m--)
    {
        int x,y;
        cin>>x>>y;
        g[x][y]=true;
    }
    memset(match,-1,sizeof match);
    int res=0;
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=n;j++)
        {
            if((i+j)%2&&!g[i][j])
            {
                memset(st,0,sizeof st);
                if(find(i,j))res++;
            }
        }
    }
    cout<<res<<endl;
    return 0;
}

376. 机器分配

#include 
using namespace std;
const int N=110;
int n,m,k;
int match[N];
bool g[N][N],st[N];
bool find(int x)
{
    for(int i=0;i<m;i++)
    {
        if(!st[i]&&g[x][i])
        {
            st[i]=true;
            if(match[i]==-1||find(match[i]))
            {
                match[i]=x;
                return true;
            }
        }
    }
    return false;
}
int main()
{
    while(cin>>n,n)
    {
        cin>>m>>k;
        memset(g,0,sizeof g);
        memset(match,-1,sizeof match);
        while(k--)
        {
            int t,a,b;
            cin>>t>>a>>b;
            if(!a||!b)continue;
            g[a][b]=true;
        }
        int res=0;
        for(int i=0;i<n;i++)
        {
            memset(st,0,sizeof st);
            if(find(i))res++;
        }
        cout<<res<<endl;
    }
    return 0;
}

4.15

1473. A+B 格式

#include 
using namespace std;
int main()
{
    int a, b;
    cin >> a >> b;
    int c = a + b;
    string num = to_string(c);
    string res;
    for (int i = num.size() - 1,j = 0; i >= 0; i--)
    {
        res += num[i];
        j++;
        if (j % 3 == 0&&i&&num[i-1]!='-')res += ",";
    }
    reverse(res.begin(),res.end());
    cout << res << endl;
    return 0;
}

1477. 拼写正确

#include 
using namespace std;
string num[15]={"zero","one","two","three","four","five","six","seven","eight","nine","ten"};
int main()
{
    string s;
    cin>>s;
    long long res=0;
    for(int i=0;i<s.size();i++)res+=s[i]-'0';
    vector<string>v;
    if(res==0)v.push_back(num[0]);
    while(res)
    {
        v.push_back(num[res%10]);
        res/=10;
    }
    for(int i=v.size()-1;i>=0;i--)cout<<v[i]<<' ';
    return 0;
    
}

1478. 签到与签出

#include 
using namespace std;
const int N=15;
struct node
{
	string id;
	string start;
	string ed;
}e[N];
int n;
bool cmp1(node a,node b)
{
	int h1=a.start[0]*10+a.start[1];
	int m1=a.start[3]*10+a.start[4];
	int s1=a.start[6]*10+a.start[7];
	int h2=b.start[0]*10+b.start[1];
	int m2=b.start[3]*10+b.start[4];
	int s2=b.start[6]*10+b.start[7];
	if(h1!=h2)return h1<h2;
	else if(m1!=m2)return m1<m2;
	else if(s1!=s2)return s1<s2;
	return true;
}
bool cmp2(node a,node b)
{
	int h1=a.ed[0]*10+a.ed[1];
	int m1=a.ed[3]*10+a.ed[4];
	int s1=a.ed[6]*10+a.ed[7];
	int h2=b.ed[0]*10+b.ed[1];
	int m2=b.ed[3]*10+b.ed[4];
	int s2=b.ed[6]*10+b.ed[7];
	if(h1!=h2)return h1>h2;
	else if(m1!=m2)return m1>m2;
	else if(s1!=s2)return s1>s2;
	return true;
}
int main()
{
	cin>>n;
	for(int i=0;i<n;i++)
	{
		string a,b,c;
		cin>>a>>b>>c;
		e[i]={a,b,c};
	}
	sort(e,e+n,cmp1);
	cout<<e[0].id<<' ';
	sort(e,e+n,cmp2);
	cout<<e[0].id;
	return 0; 
}

1519 密码

#include 
using namespace std;
int main()
{
	int n;
	cin>>n;
	int m=0;
	int s=n;
	vector<string>v;
	while(s--)
	{
		string a,b;
		cin>>a>>b;
		bool f=false;
		for(int i=0;i<b.size();i++)
		{
			if(b[i]=='1')
			{
				f=true;
				b[i]='@';
			}
			if(b[i]=='0')
			{
				f=true;
				b[i]='%';
			}
			if(b[i]=='l')
			{
				b[i]='L';
				f=true;
			}
			if(b[i]=='O')
			{
				b[i]='o';
				f=true;
			}
		}
		if(f)
		{
			m++;
			v.push_back(a+" "+b);
		}
	}
	if(m==0)
	{
	    if(n>1)
	    printf("There are %d accounts and no account is modified\n",n);
	    else puts("There is 1 account and no account is modified");
	}
	else 
	{
	    cout<<m<<endl;
		for(int i=0;i<v.size();i++)cout<<v[i]<<endl;
	}
	return 0;
}

1520. 男孩 vs 女孩

#include 
using namespace std;
const int N=110;
int n;
struct node
{
	string name;
	char sex;
	string id;
	int sum;
}a[N],b[N];
bool cmp1(node a,node b)
{
	return a.sum>b.sum;
}
bool cmp2(node a,node b)
{
	return a.sum<b.sum;
}
int main()
{
	cin>>n;
	int j=0,k=0;
	for(int i=0;i<n;i++)
	{
		string name,id;
		char sex;
		int sum;
		cin>>name>>sex>>id>>sum;
		if(sex=='F')a[j++]={name,sex,id,sum};
		else b[k++]={name,sex,id,sum};
	}
	sort(a,a+j,cmp1),sort(b,b+k,cmp2);
	bool f=false;
	if(j!=0)cout<<a[0].name<<' '<<a[0].id<<endl;
	else cout<<"Absent"<<endl,f=true;
	if(k!=0)cout<<b[0].name<<' '<<b[0].id<<endl;
	else cout<<"Absent"<<endl,f=true;
	if(!f)cout<<a[0].sum-b[0].sum<<endl;
	else cout<<"NA"<<endl;
	return 0;
	
}

1534. 字符串减法

#include 
using namespace std;
int main()
{
    string a,b;
    getline(cin,a);
    getline(cin,b);
    unordered_map<char,int>mp;
    for(int i=0;i<b.size();i++)mp[b[i]]++;
    for(int i=0;i<a.size();i++)
    {
        if(!mp.count(a[i]))cout<<a[i];
    }
    return 0;
}

1557. 说话方式

#include 
using namespace std;
#define x first
#define y second
bool check(char c)
{
    if(c>='A'&&c<='Z')return true;
    if(c>='a'&&c<='z')return true;
    if(c>='0'&&c<='9')return true;
    return false;
}
char to_lower(char c)
{
    if(c>='A'&&c<='Z')return c-'A'+'a';
}
int main()
{
    string s;
    getline(cin,s);
    unordered_map<string,int>mp;
    for(int i=0,j=0;i<s.size();i++)
    {
        if(check(s[i]))
        {
            j=i;
            while(check(s[j])&&j<s.size())j++;
            string word=s.substr(i,j-i);
            string w;
            for(int k=0;k<word.size();k++)
            w+=to_lower(word[k]);
            mp[w]++;
            i=j;
        }
    }
    int cnt=-1;
    string word;
    for(auto x:mp)
    {
        if(x.y>cnt||x.y==cnt&&x.x<word)
        {
            word=x.x;
            cnt=x.y;
        }
    }
    cout<<word<<' '<<cnt<<endl;
    return 0;
}

1547. 约会

#include 
using namespace std;
string week[10]={"MON","TUE","WED","THU","FRI","SAT","SUN"};
bool check(char c)
{
    if(c>='A'&&c<='G')return true;
    return false;
}
int cmp(char c)
{
    if(c>='A'&&c<='N')return 1;
    if(c>='0'&&c<='9')return 2;
    return 0;
}
bool judge(char c)
{
    if(c>='A'&&c<='Z')return true;
    if(c>='a'&&c<='z')return true;
    return false;
}
int main()
{
    string a,b,c,d;
    cin>>a>>b>>c>>d;
    bool f=false;
    for(int i=0;i<min((int)a.size(),(int)b.size());i++)
    {
        if(a[i]==b[i]&&check(a[i])&&!f)
        {
            f=true;
            printf("%s ",week[a[i]-'A'].c_str());
        }
        else if(a[i]==b[i]&&cmp(a[i])&&f)
        {
            if(cmp(a[i])==1)printf("%02d:",10+a[i]-'A');
            else if(cmp(a[i])==2)printf("%02d:",a[i]-'0');
            break;
        }
    }
    for(int i=0;i<min((int)c.size(),(int)d.size());i++)
    {
        if(c[i]==d[i]&&judge(c[i]))
        {
            printf("%02d",i);
            break;
        }
    }
    return 0;
}

1474. 多项式 A+B

#include 
using namespace std;
map<int,double,greater<int>>mp;
int main()
{
    for(int i=0;i<2;i++)
    {
        int k;
        cin>>k;
        for(int j=0;j<k;j++)
        {
            int x;
            double y;
            cin>>x>>y;
            mp[x]+=y;
        }
    }
    int res=0;
    for(auto x:mp)if(x.second)res++;
    printf("%d ",res);
    for(auto x:mp)
    {
        if(x.second)
        printf("%d %.1f ",x.first,x.second);
    }
    return 0;
}

1481. 多项式乘积

#include 
using namespace std;
map<int,double,greater<int>>a;
map<int,double,greater<int>>b;
map<int,double,greater<int>>c;
int main()
{
    int n;
    cin>>n;
    for(int i=0;i<n;i++)
    {
        int x;
        double y;
        cin>>x>>y;
        a[x]=y;
    }
    int m;
    cin>>m;
    for(int i=0;i<m;i++)
    {
        int x;
        double y;
        cin>>x>>y;
        b[x]=y;
    }
    for(auto x:a)
    {
        for(auto y:b)
        {
            c[x.first+y.first]+=x.second*y.second;
        }
    }
    int res=0;
    for(auto x:c)if(x.second)res++;
    printf("%d ",res);
    for(auto x:c)
    {
        if(x.second)printf("%d %.1f ",x.first,x.second);
    }
    return 0;
}

1500. 趣味数字

#include 
using namespace std;
vector<int>c;
unordered_map<int,int>ma;
unordered_map<int,int>mb;
bool add(vector<int>&a)
{
    int t=0;
    for(auto x:a)ma[x]++;
    for(int i=0;i<a.size();i++)
    {
        t+=a[i]*2;
        c.push_back(t%10);
        t/=10;
    }
    if(t)c.push_back(t);
    while(c.size()>1&&c.back()==0)c.pop_back();
    reverse(c.begin(),c.end());
    for(auto x:c)mb[x]++;
    for(auto x:ma)
    {
        for(auto y:mb)
        {
            if(x.first==y.first&&x.second!=y.second)return false;
        }
    }
    return true;
}
int main()
{
    string s;
    cin>>s;
    vector<int>v;
    for(int i=s.size()-1;i>=0;i--)v.push_back(s[i]-'0');
    if(add(v))puts("Yes");
    else puts("No");
    for(auto x:c)cout<<x;
    return 0;
}

1501. 回文数

#include 
using namespace std;
string s;
int k;
vector<int>add(vector<int>&a,vector<int>&b)
{
    int t=0;
    vector<int>c;
    for(int i=0;i<a.size();i++)
    {
        t+=a[i]+b[i];
        c.push_back(t%10);
        t/=10;
    }
    if(t)c.push_back(t);
    while(c.size()>1&&c.back()==0)c.pop_back();
    reverse(c.begin(),c.end());
    return c;
}
bool check(vector<int>a)
{
    vector<int>b;
    for(int i=a.size()-1;i>=0;i--)b.push_back(a[i]);
    return a==b;
}
int main()
{
    cin>>s>>k;
    vector<int>a;
    for(int i=s.size()-1;i>=0;i--)a.push_back(s[i]-'0');
    int cnt=0;
    while(k--)
    {
        vector<int>b;
        for(int i=a.size()-1;i>=0;i--)b.push_back(a[i]);
        if(check(a))break;
        a=add(a,b);
        cnt++;
        
    }
    for(auto x:a)cout<<x;
    cout<<endl;
    cout<<cnt<<endl;
    return 0;
}

1544. 霍格沃茨的 A + B

#include 
using namespace std;
int main()
{
    int a,b,c,d,e,f;
    scanf("%d.%d.%d %d.%d.%d",&a,&b,&c,&d,&e,&f);
    a+=d,b+=e,c+=f;
    b+=c/29;
    c%=29;
    a+=b/17;
    b%=17;
    printf("%d.%d.%d",a,b,c);
    return 0;
}

1629. 延迟回文数

#include 
using namespace std;
bool check(vector<int>&a)
{
    vector<int>b;
    for(int i=a.size()-1;i>=0;i--)b.push_back(a[i]);
    return a==b;
}
vector<int>add(vector<int>&a,vector<int>&b)
{
    vector<int>c;
    int t=0;
    for(int i=0;i<a.size();i++)
    {
        t+=a[i]+b[i];
        c.push_back(t%10);
        t/=10;
    }
    if(t)c.push_back(t);
    while(c.size()>1&&c.back()==0)c.pop_back();
    reverse(c.begin(),c.end());
    return c;
}
int main()
{
    string s;
    vector<int>a,b;
    cin>>s;
    for(int i=s.size()-1;i>=0;i--)a.push_back(s[i]-'0');
    int m=10;
    while(m--)
    {
        if(check(a))
        {
            for(auto x:a)cout<<x;
            printf(" is a palindromic number.\n");
            break;
        }
        b.clear();
        for(int i=a.size()-1;i>=0;i--)b.push_back(a[i]);
        for(int i=a.size()-1;i>=0;i--)cout<<a[i];
        cout<<" + ";
        for(int i=b.size()-1;i>=0;i--)cout<<b[i];
        cout<<" = ";
        a=add(a,b);
        for(auto x:a)cout<<x;
        cout<<endl;
        reverse(a.begin(),a.end());
    }
    if(!check(a))puts("Not found in 10 iterations.");
    return 0;
}

1476. 数叶子节点

#include 
using namespace std;
const int N=110;
const int M=N*2;
int h[N],e[M],ne[M],idx;
bool st[N];
int cnt[N];
int n,m;
int max_h;
void add(int a,int b)
{
    e[idx]=b,ne[idx]=h[a],h[a]=idx++;
}
void dfs(int u,int depth)
{
    if(h[u]==-1)
    {
        cnt[depth]++;
        max_h=max(max_h,depth);
        return;
    }
    for(int i=h[u];~i;i=ne[i])
    {
        int j=e[i];
        if(st[j])continue;
        st[j]=true;
        dfs(j,depth+1);
    }
}
int main()
{
    cin>>n>>m;
    memset(h,-1,sizeof h);
    while(m--)
    {
        int id;
        int k;
        cin>>id>>k;
        for(int i=0;i<k;i++)
        {
            int x;
            cin>>x;
            add(id,x);
        }
    }
    dfs(1,0);
    for(int i=0;i<=max_h;i++)cout<<cnt[i]<<' ';
    return 0;
}

1497. 树的遍历

#include 
using namespace std;
const int N=35;
int in[N],pos[N];
typedef struct node
{
    int data;
    node *left,*right;
}node,*tree;
int n;
tree create(int len,int *in,int *pos)
{
    if(len<=0)return nullptr;
    tree T=(tree)malloc(sizeof (struct node));
    T->left=T->right=nullptr;
    T->data=pos[len-1];
    int i=0;
    for(i=0;i<len;i++)
    {
        if(in[i]==T->data)
        {
            break;
        }
    }
    T->left=create(i,in,pos);
    T->right=create(len-i-1,in+i+1,pos+i);
    return T;
}
void bfs(tree T)
{
    queue<tree>q;
    q.push(T);
    while(q.size())
    {
        auto t=q.front();
        q.pop();
        cout<<t->data<<' ';
        if(t->left)q.push(t->left);
        if(t->right)q.push(t->right);
    }
}
int main()
{
    cin>>n;
    for(int i=0;i<n;i++)cin>>pos[i];
    for(int i=0;i<n;i++)cin>>in[i];
    tree T=create(n,in,pos);
    bfs(T);
    return 0;
}

1498. 最深的根

#include 
using namespace std;
const int N=1e4+10;
const int M=N*2+10;
int h[N],e[M],ne[M],idx;
vector<int>v;
bool st[N];
int f[N];
int n;
int max_h;
void add(int a,int b)
{
    e[idx]=b,ne[idx]=h[a],h[a]=idx++;
}
int find(int x)
{
    if(x!=f[x])f[x]=find(f[x]);
    return f[x];
}
int dfs(int u,int fa)
{
    st[u]=true;
    int depth=0;
    for(int i=h[u];~i;i=ne[i])
    {
        int j=e[i];
        if(j==fa)continue;
        if(st[j])continue;
        st[j]=true;
        depth=max(depth,dfs(j,u)+1);
    }
    return depth;
}
int main()
{
    cin>>n;
    for(int i=0;i<N;i++)f[i]=i;
    memset(h,-1,sizeof h);
    for(int i=0;i<n-1;i++)
    {
        int a,b;
        cin>>a>>b;
        if(find(a)!=find(b))f[find(a)]=find(b);
        add(a,b);
        add(b,a);
    }
    int res=0;
    for(int i=1;i<=n;i++)
    {
        if(f[i]==i)res++;
    }
    if(res>=2)printf("Error: %d components",res);
    else
    {
        for(int i=1;i<=n;i++)
        {
            memset(st,false, sizeof st);
            int depth=dfs(i,-1);
            if(depth>max_h)
            {
                v.clear();
                max_h=depth;
                v.push_back(i);
            }
            else if(depth==max_h)v.push_back(i);
        }
        for(auto x:v)cout<<x<<endl;
    }
    return 0;
}

1527. 判断二叉搜索树

#include 
using namespace std;
const int N=1010;
int n;
typedef struct node
{
    int data;
    node *left,*right;
}node,*tree;
vector<int>v1,v2,v3;
tree create1(tree T,int x)
{
    if(!T)
    {
        T=(tree)malloc(sizeof (struct node));
        T->left=T->right=nullptr;
        T->data=x;
    }
    else
    {
        if(x<T->data)T->left=create1(T->left,x);
        else T->right=create1(T->right,x);
    }
    return T;
}
tree create2(tree T,int x)
{
    if(!T)
    {
        T=(tree)malloc(sizeof (struct node));
        T->left=T->right=nullptr;
        T->data=x;
    }
    else
    {
        if(x<T->data)T->right=create2(T->right,x);
        else T->left=create2(T->left,x);
    }
    return T;
}
void pre1(tree T)
{
    if(!T)return;
    v2.push_back(T->data);
    pre1(T->left);
    pre1(T->right);
}
void pre2(tree T)
{
    if(!T)return;
    v3.push_back(T->data);
    pre2(T->left);
    pre2(T->right);
}
void pos(tree T)
{
    if (!T)return;
    pos(T->left);
    pos(T->right);
    cout << T->data << ' ';
}
int main()
{
    cin>>n;
    tree T1=nullptr,T2=nullptr;
    for(int i=0;i<n;i++)
    {
        int x;
        cin>>x;
        v1.push_back(x);
        T1=create1(T1,x);
        T2=create2(T2,x);
    }
    pre1(T1);
    pre2(T2);
    bool f=false,s=false;
    if(v1==v2)
    {
        f=true;
    }
    if(v1==v3)
    {
        s=true;
    }
    if(f&&!s)
    {
        puts("YES");
        pos(T1);
    }
    else if(!f&&s)
    {
        puts("YES");
        pos(T2);
    }
    else if(f&&s)
    {
        puts("YES");
        pos(T1);
    }
    else puts("NO");
    return 0;
}

1550.完全二叉树搜索树

#include 
using namespace std;
const int N=1010;
int n;
int tr[N];
int level[N],cnt;
void dfs(int u)
{
    if(u*2<=n)dfs(u*2);
    level[u]=tr[cnt++];
    if(u*2+1<=n)dfs(u*2+1);
}
int main()
{
    cin>>n;
    for(int i=0;i<n;i++)cin>>tr[i];
    sort(tr,tr+n);
    dfs(1);
    for(int i=1;i<=cnt;i++)cout<<level[i]<<' ';
    return 0;
}

4.16

1576. 再次树遍历

#include 
using namespace std;
const int N = 35;
int a[N], b[N];
int c[N];
int n;
string op;
int x;
int cnt1, cnt2;
int k = 0;
vector<int>v;
typedef struct node
{
	int data;
	node* left, * right;
}node, * tree;
tree create(int len, int* c, int* b)
{
	if (len <= 0)return nullptr;
	tree T = (tree)malloc(sizeof(struct node));
	T->left = T->right = nullptr;
	T->data = c[0];
	int i = 0;
	for (i = 0; i < len; i++)
		if (T->data == b[i])
			break;
	T->left = create(i, c + 1, b);
	T->right = create(len - i - 1, c + i + 1, b + i + 1);
	return T;
}
void pos(tree T)
{
	if (!T)return;
	pos(T->left);
	pos(T->right);
	v.push_back(T->data);
}
int main()
{
	cin >> n;
	while (cin >> op)
	{
		if (op == "Push")
		{
			cin >> x;
			a[cnt1++] = x;
			c[k++] = x;
		}
		else
			b[cnt2++] = a[--cnt1];
	}
		for (int i = 0; i < k; i++)cout << c[i] << ' ';
		cout << endl;
		for (int i = 0; i < cnt2; i++)cout << b[i] << ' ';
		cout<<endl;
	tree T = nullptr;
	T = create(k, c, b);
	pos(T);
	for (int i = 0; i < v.size(); i++)
	{
		cout << v[i];
		if (i < v.size() - 1)cout << ' ';
	}
	return 0;
}

1589. 构建二叉搜索树

#include 
using namespace std;
const int N = 110;
int n;
struct node
{
	int l, r;
	int data;
}tr[N];
vector<int>v;
int cnt;
void dfs(int u)
{
	//if (u == -1)return;
	if (~tr[u].l)dfs(tr[u].l);
	tr[u].data = v[cnt++];
	if (~tr[u].r)dfs(tr[u].r);
}
void bfs(int u)
{
	queue<int>q;
	q.push(u);
	while (q.size())
	{
		auto t = q.front();
		q.pop();
		cout << tr[t].data << ' ';
		if (~tr[t].l)q.push(tr[t].l);
		if (~tr[t].r)q.push(tr[t].r);
	}
}
int main()
{
	cin >> n;
	for (int i = 0; i < n; i++)
		cin >> tr[i].l >> tr[i].r;
	v.resize(n);
	for (auto& x : v)cin >> x;
	sort(v.begin(), v.end());
	dfs(0);
	bfs(0);
	return 0;
}

1592. 反转二叉树

#include 
using namespace std;
const int N=15;
bool st[N];
vector<int>leve,in;
int n;
struct node
{
    int data;
    int left,right;
}tr[N];
void bfs(int root)
{
    queue<int>q;
    q.push(root);
    while(q.size())
    {
        auto t=q.front();
        q.pop();
        leve.push_back(tr[t].data);
        if(tr[t].left!=-1)q.push(tr[t].left);
        if(tr[t].right!=-1)q.push(tr[t].right);
    }
    for(auto x:leve)cout<<x<<' ';
    cout<<endl;
}
void dfs(int root)
{
    if(tr[root].left!=-1)dfs(tr[root].left);
    in.push_back(tr[root].data);
    if(tr[root].right!=-1)dfs(tr[root].right);
}
int main()
{
    cin>>n;
    for(int i=0;i<n;i++)
    {
        tr[i].data=i;
        char x,y;
        cin>>x>>y;
        if(x=='-') tr[i].right=-1;
        else
        {
            tr[i].right=x-'0';
            st[tr[i].right]=true;
        }
        if(y=='-') tr[i].left=-1;
        else 
        {
            tr[i].left=y-'0';
            st[tr[i].left]=true;
        }
    }
    int root=0;
    for(int i=0;i<n;i++)
    {
        if(!st[i])
        {
            root=i;
            break;
        }
    }
    bfs(root);
    dfs(root);
    for(auto x:in)cout<<x<<' ';
    return 0;
}

1600. 完全二叉树

#include 
using namespace std;
const int N = 55;
struct node
{
    int l, r;
    int data;
}tr[N];
bool st[N];
int n;
int ud;
int maxv;
void check(int u, int k)
{   
    if(u==-1)return;
    if(maxv<k)
    {
        maxv=k;
        ud=u;
    }
    check(tr[u].l,k*2);
    check(tr[u].r,k*2+1);

}
int main()
{
    cin >> n;
    for (int i = 0; i < n; i++)
    {
        string a, b;
        cin >> a >> b;
        if (a != "-")
        {
            int t = 0;
            for (int i = 0; i < a.size(); i++)
                t = t * 10 + (a[i] - '0');
            tr[i].l = t;
            st[tr[i].l] = true;
        }
        else tr[i].l = -1;
        if (b != "-")
        {
            int t = 0;
            for (int i = 0; i < b.size(); i++)
                t = t * 10 + (b[i] - '0');
            tr[i].r = t;
            st[tr[i].r] = true;
        }
        else tr[i].r = -1;
        tr[i].data = i;
    }
    int root = -1;
    for (int i = 0; i < n; i++)
        if (!st[i])
        {
            root = i;
            break;
        }
    check(root, 1);
    if (maxv == n)cout << "YES " << ud << endl;
    else cout << "NO " << root << endl;
    return 0;
}

1605. 二叉搜索树的最后两层节点

#include 
using namespace std;
const int N=1010;
typedef struct node
{
    int data;
    node *left,*right;
}node ,*tree;
int n;
int cnt[N];
int max_h;
tree create(tree T,int x)
{
    if(!T)
    {
        T=(tree)malloc(sizeof (struct node));
        T->left=T->right=nullptr;
        T->data=x;
    }
    else
    {
        if(x<=T->data)
        {
            T->left=create(T->left,x);
        }
        else T->right=create(T->right,x);
    }
    return T;
}
void dfs(tree T,int depth)
{
    if(!T)return;
    if(depth>max_h) max_h=depth;
    cnt[depth]++;
    if(T->left)dfs(T->left,depth+1);
    if(T->right)dfs(T->right,depth+1);
}
int main()
{
    cin>>n;
    tree T=nullptr;
    for(int i=0;i<n;i++)
    {
        int x;
        cin>>x;
        T=create(T,x);
    }
    dfs(T,1);
    cout<<cnt[max_h]<<" + "<<cnt[max_h-1]<<" = "<<cnt[max_h]+cnt[max_h-1]<<endl;
    return 0;
}

1620. Z字形遍历二叉树

#include 
using namespace std;
const int N=35;
int n;
int in[N],pos[N];
vector<int>res;
typedef struct node
{
    int data;
    node *left,*right;
}node,*tree;
tree create(int len,int *in,int *pos)
{
    if(len<=0)return nullptr;
    tree T=(tree)malloc(sizeof (struct node));
    T->left=T->right=nullptr;
    T->data=pos[len-1];
    int i=0;
    for(i=0;i<len;i++)
    {
        if(T->data==in[i])break;
    }
    T->left=create(i,in,pos);
    T->right=create(len-i-1,in+i+1,pos+i);
    return T;
}
void bfs(tree T)
{
    queue<tree>q;
    q.push(T);
    int f=1;
    while(q.size())
    {

        vector<int>v;
        int s=q.size();
        for(int i=0;i<s;i++)
        {
            auto t=q.front();
            q.pop();
            v.push_back(t->data);
            if(t->left)q.push(t->left);
            if(t->right)q.push(t->right);
        }
        if(f!=-1)reverse(v.begin(),v.end());
        for(auto x:v)res.push_back(x);
        v.clear();
        f*=-1;
    }
}
int main()
{
    cin>>n;
    for(int i=0;i<n;i++)cin>>in[i];
    for(int i=0;i<n;i++)cin>>pos[i];
    tree T=create(n,in,pos);
    bfs(T);
    for(auto x:res)cout<<x<<' ';
    return 0;
}

1631. 后序遍历

#include 
using namespace std;
const int N=50010;
int pre[N],in[N];
int n;
typedef struct node
{
    int data;
    node *left,*right;
}node ,*tree;
vector<int>v;
tree create(int len,int *pre,int *in)
{
    if(len<=0)return nullptr;
    tree T=(tree)malloc(sizeof (struct node));
    T->left=T->right=nullptr;
    T->data=pre[0];
    int i=0;
    for(i=0;i<len;i++)
    {
        if(in[i]==T->data)break;
    }
    T->left=create(i,pre+1,in);
    T->right=create(len-i-1,pre+i+1,in+i+1);
    v.push_back(T->data);
    if(v.size()==1)
    {
        cout<<v[0];
        exit(0);
    }
    return T;
}
int main()
{
    cin>>n;
    for(int i=0;i<n;i++)cin>>pre[i];
    for(int i=0;i<n;i++)cin>>in[i];
    tree T=create(n,pre,in);
    return 0;
}

4.16 2021天梯赛模拟赛

L1-1宇宙无敌大招呼 (5分)

#include 
using namespace std;
int main()
{
    string s;
    cin>>s;
    cout<<"Hello "<<s;
    return 0;
}

L1-2考试周(5分)

#include 
using namespace std;
int main()
{
    int a,b;
    cin>>a>>b;
    double c=a*1.0/b;
    printf("%d/%.1f=%d",a,c,b);
    return 0;
}

L1-3真的恭喜你(10分)

#include 
using namespace std;
int main()
{
    int n;
    cin>>n;
    if(n>=90)
    {
        printf("gong xi ni kao le %d fen!",n);
    }
    else printf("kao le %d fen bie xie qi!",n);
}

L1-4 Cassels方程(10分)

#include 
using namespace std;
int n;
int main()
{
    cin>>n;
    while(n--)
    {
        int x,y,z;
        cin>>x>>y>>z;
        if(x*x+y*y+z*z==3*x*y*z)puts("Yes");
        else puts("No");
    }
    return 0;
}

L1-5 6翻了(15分)

#include 
using namespace std;
int main()
{
    string s;
    getline(cin,s);
    for(int i=0,j=0;i<s.size();i++)
    {
        bool f=false;
        if(s[i]=='6')
        {
            j=i;
            while(s[j]=='6')j++;
            if(j-i>3&&j-i<=9)
            {
                
                f=true;
                cout<<'9';
                i=j-1;
            }
            else if(j-i>9)
            {
                f=true;
                cout<<27;
                i=j-1;
            }
        }
        if(!f)cout<<s[i];
    }
}

L1-6 不变初心数(15分)

#include 
using namespace std;
int t;
int n;
int turn(int n)
{
    int sum=0;
    while(n)sum+=n%10,n/=10;
    return sum;
}
int main()
{
    cin>>t;
    while(t--)
    {
        cin>>n;
        set<int>s;
        for(int i=2;i<=9;i++)
        {
            int num=turn(n*i);
            s.insert(num);
        }
        if(s.size()>1)puts("NO");
        else 
        {
            for(auto x:s)cout<<x<<endl;
        }
    }

L1-7 整除光棍 (20分)

#include 
using namespace std;
int n;
int main()
{
    cin>>n;
    long long m=1;
    int wei=1;
    while(m<n)
    {
        m=m*10+1;
        wei++;
    }
    while(1)
    {
        cout<<m/n;
        m=m%n;
        if(m==0)break;
        m=m*10+1;
        wei++;
    }
    cout<<' '<<wei;
}

L1-8 编程团体赛(20分)

#include 
using namespace std;
const int N=1010;
int n;
int s[N];
int main()
{
    cin>>n;
    for(int i=0;i<n;i++)
    {
        int x,y,z;
        scanf("%d-%d%d",&x,&y,&z);
        s[x]+=z;
    }
    int maxv=-1;
    int id=-1;
    for(int i=0;i<N;i++)
    {
        if(maxv<s[i])
        {
            id=i;
            maxv=s[i];
        }
    }
    cout<<id<<' '<<maxv;
}

L2-1 彩虹瓶(25分)

#include 
using namespace std;
int n,m,k;
int main()
{
    cin>>n>>m>>k;
    while(k--)
    {
        stack<int>stk;
        bool f=false;
        int idx=1;
        for(int i=1;i<=n;i++)
        {
            int x;
            cin>>x;
            if(x!=idx)
            {
                stk.push(x);
                if(stk.size()>m)f=true;
            }
            else
            {
                idx++;
                while(stk.size()&&stk.top()==idx)idx++,stk.pop();
            }
        }
        if(!f&&idx>=n)puts("YES");
        else puts("NO");
    }
    return 0;
}

L2-2 三足鼎立(25分)

#include 
using namespace std;

int main()
{
    int n, x;
    cin >> n >> x;
    int a[n];
    for (auto &c : a) cin >> c;
    sort(a, a + n);
    long long res = 0;
    for (int i = 0; i < n; i += 1) {
        int aa = abs(x - a[i]);
        int bb = x + a[i];
        int l = i + 1;
        int r = n - 1;
        int L = -1;
        int R = -1;
        while (l <= r) {
            int mid = (l + r) / 2;
            if (a[mid] < bb && a[mid] > aa) {
                L = mid;
                r = mid - 1;
            } 
            else if (a[mid] >= bb) {
                r = mid - 1;
            } else {
                l = mid + 1;
            }
        }
        l = i + 1;
        r = n - 1;
        while (l <= r) {
            int mid = (l + r) / 2;
            if (a[mid] < bb && a[mid] > aa) {
                R = mid;
                l = mid + 1;
            } else if (a[mid] >= bb) {
                r = mid - 1;
            } else {
                l = mid + 1;
            }
        }
        if (R != -1 && L != -1) {
            res += R - L + 1;
        }
    }
    cout << res;
    return 0;
}

L2-3 这是二叉搜索树吗？(25分)

#include 
using namespace std;
const int N=1010;
int n;
typedef struct node
{
    int data;
    node *left,*right;
}node,*tree;
vector<int>v1,v2,v3;
tree create1(tree T,int x)
{
    if(!T)
    {
        T=(tree)malloc(sizeof (struct node));
        T->left=T->right=nullptr;
        T->data=x;
    }
    else
    {
        if(x<T->data)T->left=create1(T->left,x);
        else T->right=create1(T->right,x);
    }
    return T;
}
tree create2(tree T,int x)
{
    if(!T)
    {
        T=(tree)malloc(sizeof (struct node));
        T->left=T->right=nullptr;
        T->data=x;
    }
    else
    {
        if(x<T->data)T->right=create2(T->right,x);
        else T->left=create2(T->left,x);
    }
    return T;
}
void pre1(tree T)
{
    if(!T)return;
    v2.push_back(T->data);
    pre1(T->left);
    pre1(T->right);
}
void pre2(tree T)
{
    if(!T)return;
    v3.push_back(T->data);
    pre2(T->left);
    pre2(T->right);
}
vector<int>v5;
void pos(tree T)
{
    if (!T)return;
    pos(T->left);
    pos(T->right);
    v5.push_back(T->data);
}
int main()
{
    cin>>n;
    tree T1=nullptr,T2=nullptr;
    for(int i=0;i<n;i++)
    {
        int x;
        cin>>x;
        v1.push_back(x);
        T1=create1(T1,x);
        T2=create2(T2,x);
    }
    pre1(T1);
    pre2(T2);
    bool f=false,s=false;
    if(v1==v2)
    {
        f=true;
    }
    if(v1==v3)
    {
        s=true;
    }
    if(f&&!s)
    {
        puts("YES");
        pos(T1);
        bool f=false;
        for(auto x:v5)
        {
            if(f)cout<<' ';
            f=true;
            cout<<x;
        }
    }
    else if(!f&&s)
    {
        puts("YES");
        pos(T2);
        bool f=false;
        for(auto x:v5)
        {
            if(f)cout<<' ';
            f=true;
            cout<<x;
        }
    }
    else if(f&&s)
    {
        puts("YES");
        pos(T1);
        bool f=false;
        for(auto x:v5)
        {
            if(f)cout<<' ';
            f=true;
            cout<<x;
        }
    }
    else puts("NO");
    return 0;
}

L2-4 网红点打卡攻略(25分)

#include 
using namespace std;
const int N=210;
int g[N][N];
int n,m,k;
int main()
{
    cin>>n>>m;
    memset(g,0x3f,sizeof g);
    for(int i=0;i<=n;i++)g[i][i]=0;
    while(m--)
    {
        int a,b,c;
        cin>>a>>b>>c;
        g[a][b]=g[b][a]=min(g[a][b],c);
    }
    cin>>k;
    int res=0;
    int id=-1;
    int cost_min=0x3f3f3f3f;
    for(int i=1;i<=k;i++)
    {
        int num;
        bool f=false;
        int sum=0;
        cin>>num;
        set<int>s;
        vector<int>v;
        int start;
        cin>>start;
        s.insert(start);
        v.push_back(start);
        int last=start;
        if(g[0][start]!=0x3f3f3f3f)sum+=g[0][start];
        else 
        {
            f=true;
            continue;
        }
        for(int j=1;j<num;j++)
        {
            int x;
            cin>>x;
            s.insert(x);
            v.push_back(x);
            if(g[last][x]!=0x3f3f3f3f)
            {
                sum+=g[last][x];
            }
            else 
            {
                f=true;
                continue;
            }
            last=x;
        }
        if(f)continue;
        if(g[last][0]!=0x3f3f3f3f)
        {
            sum+=g[last][0];
        }
        else
        {
            f=true;
            continue;
        }
        if(s.size()==n&&v.size()==n)
        {
            res++;
            if(cost_min>sum)
            {
                cost_min=sum;
                id=i;
            }
        }
    }
    cout<<res<<endl;
    cout<<id<<' '<<cost_min<<endl;
    return 0;
}

4.18

1539. 等重路径

#include 
using namespace std;
const int N=110;
int h[N],e[N],ne[N],idx;
int n,m,k;
int w[N];
vector<vector<int>>ans;
vector<int>path;
void add(int a,int b)
{
    e[idx]=b,ne[idx]=h[a],h[a]=idx++;
}
void dfs(int u,int s,vector<int>&path)
{
    if(h[u]==-1)
    {
        if(s==k)ans.push_back(path);
        return;
    }
    for(int i=h[u];~i;i=ne[i])
    {
        int j=e[i];
        path.push_back(w[j]);
        dfs(j,s+w[j],path);
        path.pop_back();
    }
   
}
int main()
{
    cin>>n>>m>>k;
    memset(h,-1,sizeof h);
    for(int i=0;i<n;i++)cin>>w[i];
    for(int i=0;i<m;i++)
    {
        int k,id;
        cin>>id>>k;
        for(int j=0;j<k;j++)
        {
            int x;
            cin>>x;
            add(id,x);
        }
    }
    path.push_back(w[0]);
    dfs(0,w[0],path);
    sort(ans.begin(),ans.end(),greater<vector<int>>());
    for(auto x:ans)
    {
        for(int i=0;i<x.size();i++)cout<<x[i]<<' ';
        cout<<endl;
    }
    return 0;
}

1584. 最大的一代

#include 
using namespace std;
const int N=210;
int h[N],e[N],ne[N],idx;
int cnt[N];
int max_h;
int n,m;
void add(int a,int b)
{
    e[idx]=b,ne[idx]=h[a],h[a]=idx++;
}
void dfs(int u,int depth)
{    
    max_h=max(depth,max_h);
    cnt[depth]++;
    for(int i=h[u];~i;i=ne[i])
    {
        int j=e[i];
        dfs(j,depth+1);
    }
}
int main()
{
    cin>>n>>m;
    memset(h,-1,sizeof h);
    while(m--)
    {
        int id,k;
        cin>>id>>k;
        for(int i=0;i<k;i++)
        {
            int x;
            cin>>x;
            add(id,x);
        }
    }
    dfs(1,1);
    int res=0,level=0;
    for(int i=1;i<=max_h;i++)
    {
        if(res<cnt[i])
        {
            res=cnt[i];
            level=i;
        }
    }
    cout<<res<<' '<<level<<endl;
    return 0;
}

1565. 供应链总销售额

#include 
using namespace std;
int n;
double p,r;
const int N=1e5+10;
int h[N],e[N],ne[N],idx;
double w[N];
double res;
int max_h;
void add(int a,int b)
{
    e[idx]=b,ne[idx]=h[a],h[a]=idx++;
}
void dfs(int u,int depth)
{
    max_h=max(max_h,depth);
    if(h[u]==-1)
    {
        res+=p*w[u]*pow(1+r,depth);
        return;
    }
    for(int i=h[u];~i;i=ne[i])
    {
        int j=e[i];
        dfs(j,depth+1);
    }
}
int main()
{
    memset(h,-1,sizeof h);
    cin>>n>>p>>r;
    r/=100;
    for(int i=0;i<n;i++)
    {
        int k;
        cin>>k;
        if(k)
        {
            for(int j=0;j<k;j++)
            {
                int id;
                cin>>id;
                add(i,id);
            }
        }
        else
        {
            int x;
            cin>>x;
            w[i]=x;
        }
    }
    dfs(0,0);
    printf("%.1f", res);
    return 0;
}

1580. 供应链最高价格

#include 
using namespace std;
int n;
double p,r;
const int N=1e5+10;
int h[N],e[N],ne[N],idx;
int max_h;
double res;
unordered_map<double,int>mp;
void add(int a,int b)
{
    e[idx]=b,ne[idx]=h[a],h[a]=idx++;
}
void dfs(int u,int depth)
{
    max_h=max(depth,max_h);
    if(h[u]==-1)
    {
        double w=p*pow(1+r,depth);
        if(res<w)res=w,mp[res]++;
        else if(res==w)mp[res]++;
        return;
    }
    for(int i=h[u];~i;i=ne[i])
    {
        int j=e[i];
        dfs(j,depth+1);
    }
}
int main()
{
    cin>>n>>p>>r;
    memset(h,-1,sizeof h);
    r/=100;
    int root=0;
    for(int i=0;i<n;i++)
    {
        int x;
        cin>>x;
        if(x==-1)root=i;
        else add(x,i);
    }
    dfs(root,0);
    printf("%.2f %d",res,mp[res]);
    return 0;
}

1596. 供应链最低价格

#include 
using namespace std;
const int N=1e5+10;
int h[N],e[N],ne[N],idx;
double q,r;
int n;
double res=1e9;
int max_h;
unordered_map<double,int>mp;
void add(int a,int b)
{
    e[idx]=b,ne[idx]=h[a],h[a]=idx++;
}
void dfs(int u,int depth)
{
    max_h=max(max_h,depth);
    if(h[u]==-1)
    {
        double w=q*pow(1+r,depth);
        if(res>w)res=w,mp[res]++;
        else if(res==w)mp[res]++;
    }
    for(int i=h[u];~i;i=ne[i])
    {
        int j=e[i];
        dfs(j,depth+1);
    }
}
int main()
{
    cin>>n>>q>>r;
    r/=100;
    memset(h,-1,sizeof h);
    for(int i=0;i<n;i++)
    {
        int k;
        cin>>k;
        for(int j=0;j<k;j++)
        {
            int x;
            cin>>x;
            add(i,x);
        }
    }
    dfs(0,0);
    printf("%.4f %d",res,mp[res]);
    return 0;
}

1649. 堆路径

#include 
using namespace std;
const int N=1010;
vector<int>v;
vector<int>path;
vector<vector<int>>ans;
int n;
bool is_great=true,is_min=true;
void dfs(int u)
{
    if(u*2>n)
    {
        ans.push_back(path);
        for(int i=1;i<path.size();i++)
        {
            if(path[i-1]>path[i])is_min=false;
            if(path[i-1]<path[i])is_great=false;
        }
        return;
    }
    if(u*2+1<=n)
    {
        path.push_back(v[u*2+1]);
        dfs(u*2+1);
        path.pop_back();
    }
    if(u*2<=n)
    {
        path.push_back(v[u*2]);
        dfs(u*2);
        path.pop_back();
    }
}
int main()
{
    cin>>n;
    v.resize(n+1);
    for(int i=1;i<=n;i++)cin>>v[i];
    path.push_back(v[1]);
    dfs(1);
    for(auto x:ans)
    {
        for(int i=0;i<x.size();i++)cout<<x[i]<<' ';
        cout<<endl;
    }
    if(is_great&&!is_min)puts("Max Heap");
    else if(is_min&&!is_great)puts("Min Heap");
    else puts("Not Heap");
}

1623. 中缀表达式

#include
using namespace std;
const int N=21;
struct node
{
    string data;
    int left,right;
}tr[N];
int n;
bool is_leaf[N];
bool st[N];
string dfs(int u)
{
    string left,right;
    if(tr[u].left!=-1)
    {
        left=dfs(tr[u].left);
        if(!is_leaf[tr[u].left])
        left="("+left+")";
    }
    if(tr[u].right!=-1)
    {
        right=dfs(tr[u].right);
        if(!is_leaf[tr[u].right])
        right="("+right+")";
    }
    return left+tr[u].data+right;
}
int main()
{
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        cin>>tr[i].data>>tr[i].left>>tr[i].right;
        if(tr[i].left!=-1)st[tr[i].left]=true;
        if(tr[i].right!=-1)st[tr[i].right]=true;
        if(!st[tr[i].left]&&!st[tr[i].right])is_leaf[i]=true;
    }
    int root=-1;
    for(int i=1;i<=n;i++)
    {
        if(!st[i])
        {
            root=i;
            break;
        }
    }
   cout<< dfs(root)<<endl;
   return 0;
}

1475. 紧急情况

#include 
using namespace std;
const int N=510;
int g[N][N];
int dist[N];
bool st[N];
int w[N];
int sum_w[N];
int cnt[N];
int pre[N];
int n,m,s,d;
void dijkstra()
{
    memset(dist,0x3f,sizeof dist);
    sum_w[s]=w[s];
    dist[s]=0;
    cnt[s]=1;
    for(int i=0;i<n;i++)
    {
        int t=-1;
        for(int j=0;j<n;j++)
            if(!st[j]&&(t==-1||dist[j]<dist[t]))
                t=j;
        st[t]=true;
        for(int j=0;j<n;j++)
        {
            if(dist[j]>dist[t]+g[t][j])
            {
                dist[j]=dist[t]+g[t][j];
                cnt[j]=cnt[t];
                sum_w[j]=sum_w[t]+w[j];
                pre[j]=t;
            }
            else if(dist[j]==dist[t]+g[t][j])
            {
                cnt[j]+=cnt[t];
              //  if(sum_w[j]
                {
                    sum_w[j]=max(sum_w[j],sum_w[t]+w[j]);
                    pre[j]=t;
                }
            }
        }
    }
    cout<<cnt[d]<<' '<<sum_w[d]<<endl;
}
int main()
{
    cin>>n>>m>>s>>d;
    for(int i=0;i<n;i++)cin>>w[i];
    memset(g,0x3f,sizeof g);
    for(int i=0;i<n;i++)g[i][i]=0;
    
    for(int i=0