POJ - 3660 Cow Contest

 

 代码如下：

#include<cmath>
#include<cstdio>
#include<iostream>
#include<algorithm>
#include<stack>
#include<cstring>
#include<queue>
using namespace std;

bool a[120][120];

int n, m;
int main(){
    while(scanf("%d%d", &n, &m) != EOF)
    {
        for(int i = 0; i <= n; i ++ )
            for(int j = 0; j <= n; j ++ ) 
                a[i][j] = false;

        for(int i = 0; i < m; i ++ )
        {
            int ff, tt;
            scanf("%d%d", &ff, &tt);
            a[ff][tt] = true;
        }

        for(int k = 1; k <= n; k ++ )
            for(int i = 1; i <= n; i ++ )
                for(int j = 1; j <= n; j ++ )
                    if(i == j) continue;
                    else a[i][j] = a[i][j] || (a[i][k] && a[k][j]);
        
        int ans = 0;

        for(int i = 1; i <= n; i ++ )
        {
            bool pass = true;
            for(int j = 1; j <= n; j ++ )
                if(i == j) continue;
                else if(!(a[i][j] || a[j][i])) 
                {
                    pass = false;
                    break;
                }
            
            if(pass) ans ++ ;
        }

        printf("%d\n", ans);
                
    }


    system("pause");
    return 0;

}