牛客练习赛61题解

牛客练习赛61 题解

A:正义感爆棚去打怪

#include
using namespace std;
int main(){
    int t;
    scanf("%d",&t);
    while(t--){
        int h,a,H,A;
        scanf("%d %d %d %d",&h,&a,&H,&A);
        int num=(H+a-1)/a;
        int now=(num-1)*A;
        if(now==0){
            puts("-1");
            continue;
        }
        int x=h/now;
        int y=h-x*now;
        if(y==0){
            x--;y+=now;
        }
        bool f=1;
        while(1){
            H-=a;if(H<=0)break;
            y-=A;if(y<=0){
            f=0;break;}
        }
        x+=f;
        printf("%d\n",x);
    }
	return 0;
}

B：打怪累了吃水果充饥

#include
using namespace std;
int main(){
    int t;
    scanf("%d",&t);
    while(t--){
        int n,m;
        scanf("%d %d",&n,&m);
        if(n>m)swap(n,m);
            int now=n;
            int num=0;
            while(now

C:吃完水果去考数学

#include
using namespace std;
typedef pair pii;
int fa[14],num[14],cnt,ans[14];
int _find(int x){
    if(fa[x]==x)return x;
    else return fa[x]=_find(fa[x]);
}
int dfs(int a,int b,int c,int d,int num){
    if(num==0)return 1;
    int res=0;
    if(a>=ans[num])res+=dfs(a-ans[num],b,c,d,num-1);
    if(b>=ans[num])res+=dfs(a,b-ans[num],c,d,num-1);
    if(c>=ans[num])res+=dfs(a,b,c-ans[num],d,num-1);
    if(d>=ans[num])res+=dfs(a,b,c,d-ans[num],num-1);
    return res;
}
int main(){
    for(int i=1;i<=12;i++)fa[i]=i,num[i]=1;
    int a,b,c,d,m;scanf("%d %d %d %d %d",&a,&b,&c,&d,&m);
    for(int i=1;i<=m;i++){
        int x,y;scanf("%d %d",&x,&y);
        int u=_find(x),v=_find(y);
        if(u==v)continue;
        fa[u]=v;num[v]+=num[u];
    }
    for(int i=1;i<=12;i++)
        if(_find(i)==i)
            ans[++cnt]=num[i];
    printf("%d\n",dfs(a,b,c,d,cnt));
	return 0;
}

D：考完试解放去旅游

#include
using namespace std;
typedef long long LL;
typedef pair pii;
const int N=1e5+10;
LL n,m,ans;
LL d1[N],d2[N],x[N<<1],y[N<<1],z[N<<1];

LL cnt=1,head[N],to[N<<1],nxt[N<<1],len[N<<1];
void add_edge(LL x,LL y,LL z) {
    nxt[++cnt]=head[x]; to[cnt]=y; len[cnt]=z; head[x]=cnt;
}

bool vis[N];
priority_queue q;
void Dijkstra(LL d[],LL s) {
    while (!q.empty()) q.pop();
    memset(vis,0,sizeof(vis));
    d[s]=0; q.push(make_pair(0,s));
    while (!q.empty()) {
        pii x=q.top(); q.pop();
        if (vis[x.second]) continue;
        vis[x.second]=1;
        for (LL i=head[x.second];i;i=nxt[i]) {
            LL y=to[i];
            if (d[y]>d[x.second]+len[i]) {
                d[y]=d[x.second]+len[i];
                q.push(make_pair(-d[y],y));
            }
        }
    }
}

int main()
{
    scanf("%d %d",&n,&m);
    for (int i=1;i<=m;i++) scanf("%lld%lld%lld",&x[i],&y[i],&z[i]);

    memset(d1,0x3f,sizeof(d1)); memset(d2,0x3f,sizeof(d2));
    for (int i=1;i<=m;i++) add_edge(x[i],y[i],z[i]);
    Dijkstra(d1,1);

    cnt=1; memset(head,0,sizeof(head));
    for (int i=1;i<=m;i++) add_edge(y[i],x[i],z[i]);
    Dijkstra(d2,n);

    ans=d1[n];
    int q;scanf("%d",&q);
    for (int j=1;j<=q;j++){
        int i;scanf("%d",&i);
        if (ans>d1[y[i]]+d2[x[i]]+z[i]) puts("YES");
        else puts("NO");
    }
    return 0;
}

E：旅游结束去学英语

#include
using namespace std;
typedef long long ll;
typedef pair pii;
const int N=2e5+10;
unordered_map>mp;
int k,n;
ll hash1[N],pow26[N];
char s[N];
void init(){
    pow26[0]=1;
    for(int i=1;i<=n;i++)pow26[i]=pow26[i-1]*131;
    for(int i=1;i<=n;i++)hash1[i]=hash1[i-1]+(s[i]-'a')*pow26[i];
}
bool check(int mid){
    mp.clear();
    for(int i=mid;i<=n;i++){
        ll has=(hash1[i]-hash1[i-mid])*pow26[n-i];
        mp[has].push_back({i-mid+1,i});
    }
    for(auto it:mp){
        int last=0;
        int now=0;
        for(auto is:it.second){
            if(is.first>last){
                now++;
                last=is.second;
            }
        }
        if(now>=k)return true;
    }
    return false;
}
int main()
{
    scanf("%d %d",&n,&k);scanf(" %s",s+1);
    init();
    int l=1,r=n,ans=0;
    while(l<=r){
        int mid=(l+r)>>1;
        if(check(mid)){
            l=mid+1;
            ans=mid;
        }else r=mid-1;
    }
    printf("%d\n",ans);
    return 0;
}

F:英语学累了，吃个苹果压压惊

#include 
#include 
#include 
using namespace std;
const int N=1e5+10;
const int M=2e7;
const int INF=2e9;
int head[N],cnt,cnt1,n,q,fa[N][18],ans,root1[N],root,totsiz,sum[M],son[M][2],vn[N],siz[N],dep[N],mx[N],num1[N],d[N];
bool vis[N];
struct edge{
    int next,to,w;
}e[N<<1];
void add(int u,int v,int w){
    e[++cnt].next=head[u];
    e[cnt].to=v;
    e[cnt].w=w;
    head[u]=cnt;
}
inline void dfs(int u,int f,int di){
    dep[u]=di;d[u]=d[f]+1;fa[u][0]=f;
    for(int i=head[u];i;i=e[i].next){
        int v=e[i].to;if(v==f)continue;
        dfs(v,u,di+e[i].w);
    }
}
void init1(){
    dfs(1,0,0);
    for(int j=0;(1<<(j+1))d[v])swap(u,v);int temp=d[v]-d[u];
    for(int i=0;(1<=0;i--){
        if(fa[u][i]!=fa[v][i]){
            u=fa[u][i];v=fa[v][i];
        }
    }
    return fa[u][0];
}
int getdis(int u,int v){return dep[u]+dep[v]-2*dep[LCA(u,v)];}
inline void get_root(int u,int f){
    mx[u]=0,siz[u]=1;
    for(int i=head[u];i;i=e[i].next){
        int v=e[i].to;if(v==f||vis[v])continue;
        get_root(v,u);siz[u]+=siz[v];mx[u]=max(mx[u],siz[v]);
    }
    mx[u]=max(mx[u],totsiz-mx[u]);if(mx[u]siz[u]?size-siz[u]:siz[v];root=0;
        get_root(v,0),vn[root]=u,dfs2(root,0);
    }
}
inline void init(){
    root=0,mx[0]=n+1,totsiz=n;get_root(1,0),dfs2(root,0);
}
inline int query(int p,int l,int r,int x,int y){
    if(!p)return INF;if(x<=l&&r<=y)return sum[p];
    int mid=(l+r)>>1,tmp=INF;
    if(x<=mid)tmp=min(tmp,query(son[p][0],l,mid,x,y));
    if(y>mid)tmp=min(tmp,query(son[p][1],mid+1,r,x,y));
    return tmp;
}
inline void query(int x,int l,int r){
    for(int i=x;i;i=vn[i]){
        ans=min(ans,getdis(x,i)+query(root1[i],1,10000,l,r));
    }
}
inline void change(int &p,int l,int r,int x,int y){
    if(!p)p=++cnt1,sum[p]=INF;sum[p]=min(sum[p],y);
    if(l==r)return;int mid=(l+r)>>1;
    if(x<=mid)change(son[p][0],l,mid,x,y);
    else change(son[p][1],mid+1,r,x,y);
}
inline void change(int x,int y){
    for(int i=x;i;i=vn[i]){
        change(root1[i],1,10000,y,getdis(i,x));
    }
}
inline void changes(){for(int i=1;i<=n;i++)change(i,num1[i]);}
int main(){
    scanf("%d %d",&n,&q);
    for(int i=1;i<=n;i++)scanf("%d",&num1[i]);
    for(int i=1;i