牛客小白月赛25
A AOE还是单体？
#include
#define int ll
typedef long long ll;
const int INF = 0x3f3f3f3f3f;
const int mod = 1e9 + 7;
const int maxn = 2e5 + 10;
const int N = 50;
using namespace std;
int a[maxn];
void solve() {
int n,x,sum=0;
cin>>n>>x;
for(int i=0;i<n;i++) cin>>a[i];
sort(a,a+n);
int top=n;
while (top>n-x&&top>0) sum+=a[--top];
cout<<sum;
}
signed main() {
int _ = 1;
while (_--) {
solve();
}
return 0;
}
B k-size字符串
#include
using namespace std;
#define ll long long
const int mod=1e9+7;
ll power(ll a,ll b){
ll res=1;
while(b){
if(b&1)res=res*a%mod;
b>>=1,a=a*a%mod;
}
return res;
}
ll inv(ll x){return power(x,mod-2);}
ll C(ll a,ll b){
ll t=1;
for(int i=1;i<=b;i++)t=t*(a-i+1)%mod*inv(i)%mod;
return t;
}
ll f(ll n,ll m){
if(n<=0||m<0)return 0;
return C(n+m-1,m);
}
int main(){
ll n,m,k;
cin>>n>>m>>k;
if(k&1)
cout<<(f(k/2+1,n-k/2-1)*f(k/2,m-k/2)+f(k/2,n-k/2)*f(k/2+1,m-k/2-1))%mod;
else cout<<2*f(k/2,n-k/2)*f(k/2,m-k/2)%mod;
}
C 白魔法师
#include
#define int ll
typedef long long ll;
const int INF = 0x3f3f3f3f3f;
const int mod = 1e9 + 7;
const int maxn = 1e5 + 10;
const int N = 50;
using namespace std;
int n,fa[maxn],num[maxn];
char s[maxn];
vector<int >g[maxn];
int findfa(int x){
return fa[x]==x?x:fa[x]=findfa(fa[x]);
}
void solve() {
cin>>n>>s+1;
for(int i=1;i<=n;i++)fa[i]=i,num[i]=1;
for(int i=1,u,v;i<n;i++){
cin>>u>>v;
g[u].push_back(v);
g[v].push_back(u);
if (s[v]=='W'&&s[u]=='W'){
int fx=findfa(u),fy=findfa(v);
if (fx!=fy) fa[fx]=fy,num[fy]+=num[fx];
}
}
int max_=0;
for (int i = 1; i< n; ++i) {
int res=1;
if (s[i]=='W'){
res=num[findfa(i)];
} else{
for(int j=0;j<g[i].size();j++){
int v=g[i][j];
if (s[v]=='W') res+=num[findfa(v)];
}
}
max_=max(res,max_);
}
cout<<max_;
}
signed main() {
int _ = 1;
while (_--) {
solve();
}
return 0;
}
D 抽卡
#include
#define int ll
typedef long long ll;
const int INF = 0x3f3f3f3f3f;
const int mod = 1e9 + 7;
const int maxn = 1e5 + 10;
const int N = 50;
using namespace std;
int aa[maxn],bb[maxn];
int power(int a,int b){return b?power(a*a%mod,b/2)*(b%2?a:1)%mod:1;}
int inv(int x){return power(x,mod-2);}
void solve() {
int n,sum=1;
cin>>n;
for (int i = 0; i < n; ++i) cin>>aa[i];
for (int i = 0; i < n; ++i) cin>>bb[i];
for (int i = 0; i < n; ++i)
sum=sum*(aa[i]-bb[i])%mod*inv(aa[i])%mod;
cout<<(mod+1-sum)%mod;
}
signed main() {
int _ = 1;
while (_--) {
solve();
}
return 0;
}
E 点击消除
#include
#define int ll
typedef long long ll;
const int INF = 0x3f3f3f3f3f;
const int mod = 1e9 + 7;
const int maxn = 3e5 + 10;
const int N = 50;
using namespace std;
char a[maxn];
void solve() {
string s;
cin>>s;
int top=0;
a[0]=s[0];
for (int i = 1; i < s.size(); ++i) a[top]==s[i]?top--:a[++top]=s[i];
if (top==-1) cout<<0;
for (int i = 0; i <=top; ++i) cout<<a[i];
}
signed main() {
int _ = 1;
while (_--) {
solve();
}
return 0;
}
F 疯狂的自我检索者
#include
#define int ll
typedef long long ll;
const int INF = 0x3f3f3f3f3f;
const int mod = 1e9 + 7;
const int maxn = 1e6 + 10;
const int N = 50;
using namespace std;
void solve() {
int n,m,sum=0;
cin>>n>>m;
for(int i=0;i<n-m;i++){
int x;
cin>>x;
sum+=x;
}
cout<<setiosflags(ios::fixed)<<setprecision(5)<<(sum+m)*1.0/n<<" "<<1.0*(sum+m*5)/n;
}
signed main() {
int _ = 1;
while (_--) {
solve();
}
return 0;
}
G 解方程
#include
#define int ll
typedef long long ll;
const int INF = 0x3f3f3f3f3f;
const int mod = 1e9 + 7;
const int maxn = 1e6 + 10;
const int N = 50;
using namespace std;
void solve() {
long double a,b,c;
cin>>a>>b>>c;
long double l=0,r=1e9,mid;
while (r-l>1e-8){
mid=(l+r)/2;
long double y=pow(mid,a)+b*log(mid);
if (y<c) l=mid;
else r=mid;
}
cout<<setprecision(8)<<mid;
}
signed main() {
int _ = 1;
while (_--) {
solve();
}
return 0;
}
H 神奇的字母（二）
#include
#define int ll
typedef long long ll;
const int INF = 0x3f3f3f3f3f;
const int mod = 1e9 + 7;
const int maxn = 1e6 + 10;
const int N = 50;
using namespace std;
int a[30]={0};
void solve() {
string s;
while (cin>>s)
for (int i = 0; i < s.size(); ++i)
a[s[i]-'a']++;
int max_=0;
for (int i = 0; i < 26; ++i)
if (a[max_]<a[i])
max_=i;
cout<<(char)(max_+'a');
}
signed main() {
int _ = 1;
while (_--) {
solve();
}
return 0;
}
I 十字爆破
#include
#define int ll
typedef long long ll;
const int INF = 0x3f3f3f3f3f;
const int mod = 1e9 + 7;
const int maxn = 1e6 + 10;
const int N = 50;
using namespace std;
vector<int > a[maxn];
int nn[maxn],mm[maxn];
void solve() {
int n,m;
cin>>n>>m;
for(int i=0;i<n;i++) nn[i]=0;
for(int i=0;i<m;i++) mm[i]=0;
for (int i = 0; i < n; ++i) {
for (int j = 0; j <m; ++j) {
int x;
cin>>x;
a[i].push_back(x);
nn[i]+=x;
mm[j]+=x;
}
}
for (int i = 0; i < n; ++i) {
for (int j = 0; j < m; ++j) {
cout << nn[i] + mm[j] - a[i][j]<<" ";
}
cout << endl;
}
}
signed main() {
int _ = 1;
while (_--) {
solve();
}
return 0;
}
J 异或和之和
#include
#define int ll
typedef long long ll;
const int INF = 0x3f3f3f3f3f;
const int mod = 1e9 + 7;
const int maxn = 5e5 + 10;
const int N = 50;
using namespace std;
int on[70]={0};
int n,sum=0;
int c(int a){
if (a<2||n<3) return 0;
return ((n-a>1?(n-a)*a*(n-a-1)/2:0)%mod+(a>2?a*(a-1)*(a-2)/6:0)%mod)%mod;
}
void solve() {
cin>>n;
for (int i = 0,x,b; i < n; ++i) {
cin>>x,b=0;
while (x) x&1?on[b]++:0,b++,x>>=1;
}
for (int i = 0,k=1; i < 64; ++i,k*=2)
sum+=k%mod*c(on[i]),sum%=mod;
cout<<sum;
}
signed main() {
ios::sync_with_stdio(0),cin.tie(0), cout.tie(0);
int _ = 1;
while (_--) {
solve();
}
return 0;
}
