牛客练习赛24

#include<stdio.h>
#include<algorithm>
#include<cmath>
#include<iostream>
using namespace std;
const int mod = 1e9 + 7;
long long quick_power(long long a, long long n)
{
	long long ans = 1;
	while (n != 0)
	{
		if (n & 1)
		{
			ans = (ans * a) % mod;
		}
		a = (a * a) % mod;
		n = n >> 1;
	}
	return ans;
}
int main()
{
	int n, m;
	while (scanf("%d%d", &n, &m) != EOF)
	{
		long long ans = m * quick_power(m - 1, n - 1)%mod;
		printf("%lld\n", ans);
	}
}

#include <bits/stdc++.h>
using namespace std;
const int N=1e6+5;
int f[N],cnt[N];
int fa(int a)
{
	return f[a]==a?a:f[a]=fa(f[a]);
}
int main()
{
 	int n,ans=0;
 	scanf("%d",&n);
	for(int i=0;i<=n;i++)f[i]=i;
	int x,y;
	for(int i=0;i<n-1;i++)
	    {
	    	scanf("%d %d",&x,&y);
	    	if(x!=1&&y!=1)
	    	x=fa(x),y=fa(y),f[x]=y;
		 } 
	for(int i=0;i<=n;i++)
	     ++cnt[fa(i)];
   for(int i=0;i<=n;i++)
       ans=max(cnt[i],ans);
	   printf("%d\n",ans); 
  return 0;	
} 

#include <bits/stdc++.h>
using namespace std;
const int N=1000005;
typedef pair<int,int> pii;

int R[N],B[N];
int main()
{
	cin.tie(0); cout.tie(0);
	std::ios::sync_with_stdio(0);
	int n,m;
	int r=0,b=0;
	char to;
	scanf("%d %d",&n,&m);

	getchar();
	for(int i=1;i<=n;i++)
	{
		scanf("%c",&to);
		if(to=='R')
		{
		  R[++r]=i;
		}else {
			 B[++b]=i;
		    }
	}

	getchar();
	int q;
	for(int i=1;i<=m;i++)
	{
		scanf("%c %d",&to,&q);
		getchar();
		if(to=='R')
		{
			if(q>r)printf("-1\n");
			else printf("%d\n",R[q]);
		}else
		{
			if(q>b)printf("-1\n");
			else printf("%d\n",B[q]);
		
		}
	}
	return 0;
}

#include<bits/stdc++.h>
using namespace std;
int book[50001],ans;
int visit[50001];
typedef pair<int,int> pill;
vector<pill> v[50001];
void dfs(int d,int va)
{
	int size=v[d].size();
	if(size==0){
		ans=max(ans,va);
		return;
	}
	for(int i=0;i<size;i++)
	{
		int fw=v[d][i].first;

		dfs(fw,va+v[d][i].second);

	}
}
int main()
{
	int n,root;
	scanf("%d",&n);
	ans=0;
	for(int i=1;i<=n;i++)visit[i]=0,book[i]=0,v[i].clear();
	for(int i=0;i<n-1;i++)
	{
		int in,to,vi;
		scanf("%d %d %d",&in,&to,&vi);
		v[to].push_back(pill(in,vi));
		book[in]=1;
	}
	for(int i=1;i<=n;i++)
	{
		if(book[i]==0)
		{
			root=i; break;
		}
	}
	dfs(root,0);
	printf("%d\n",ans);
	return 0;
}

#include <iostream>
#include <algorithm>
using namespace std;
int map[300][300];
int book[300];
int ans[300];
int sum = 999, m, n;
void dfs(int k, int total)
{
	if (total >= sum)
		return;
	if(total>(m-k+sum))        
	 return;
	ans[k]=min(ans[k],total);
	if (k == m)
	{
		sum = min(sum, total);
		return;
	}
	for (int i = 1; i <= m; i++)
	{
		if (map[k][i] != 0 && book[i] == 0)
		{
			book[i] = 1;
			if((total + map[k][i])<ans[i])
			dfs(i,total + map[k][i]);
			book[i] = 0;
		}
	}
}
int main()
{
	int a, b;
	scanf("%d%d", &m, &n);
	sum=m;
	for(int i=0;i<=m;i++)ans[i]=9999;
	map[0][1]=1;
	map[1][0]=1;
	for (int i = 2; i < 240; i++)
	{
		map[i - 1][i] = 1;
		map[i][i - 1] = 1;
	}
	for (int i = 0; i < n; i++)
	{
		scanf("%d%d", &a, &b);
		map[a][b] = 1;
	}
	book[1] = 1;
	dfs(1, 1);
	printf("%d\n", sum);
	return 0;
}

#include<cstdio>
#include<iostream>
#include<cstring>
using namespace std;
typedef long long ll;
const int N=50010,mo=19260817;
int f[N],n,m;
int main(){
    cin>>n>>m;
    f[0]=1;
    for (int i=1;i<=n;i++){
        int x;scanf("%d",&x);
        for (int j=x;j<=m;j++){
            f[j]+=f[j-x];
            if (f[j]>mo)f[j]-=mo;
        }
    }
    int ans=0;
    for (int i=1;i<=m;i++)(ans+=f[i])%=mo;
    cout<<ans<<endl;  
}