poj3401二分图

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <climits>
#include <string>
#include <iostream>
#include <map>
#include <cstdlib>
#include <list>
#include <set>
#include <queue>
#include <stack>
#include<math.h>
using namespace std;
const int maxn= 555;

int link[maxn];
int Map[maxn][maxn];
int n;
const int INF=0xfffffff;
int used[maxn];
int dfs(int x)
{
    for(int i=1;i<=n;i++){
        if(!used[i]&&Map[x][i]){
            used[i]=1;
            if(link[i]==-1||dfs(link[i])){
                link[i]=x;
                return 1;
            }
        }
    }
    return 0;
}

void gao()
{
    int ans=0;
    memset(link,-1,sizeof(link));
    for(int i=1;i<=n;i++){
        memset(used,0,sizeof(used));
        if(dfs(i)) ans+=1;
    }
    cout<<ans<<endl;
}

int main()
{
    int k;
    while(scanf("%d%d",&n,&k)!=EOF){
        memset(Map,0,sizeof(Map));
        for(int i=0;i<k;i++){
            int a;int b;
            scanf("%d%d",&a,&b);
            Map[a][b]=1;
        }
        gao();
    }
    return 0;
}