【poj1274】 The Perfect Stall

http://poj.org/problem?id=1274 (题目链接)

题意

　　懒得写了

Solution

　　二分图匹配裸题。注意清空数组。

代码

// poj3020
#include<algorithm>
#include<iostream>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<cmath>
#define LL long long
#define inf 2147483640
#define Pi 3.1415926535898
#define free(a) freopen(a".in","r",stdin),freopen(a".out","w",stdout);
using namespace std;

const int maxn=500;
struct edge {int next,to;}e[maxn<<2];
int head[maxn],p[maxn],vis[maxn],cnt,n,m;

void insert(int u,int v) {
    e[++cnt].to=v;e[cnt].next=head[u];head[u]=cnt;
}
bool find(int x) {
    for (int i=head[x];i;i=e[i].next) if (!vis[e[i].to]) {
            vis[e[i].to]=1;
            if (p[e[i].to]==0 || find(p[e[i].to])) {
                p[e[i].to]=x;
                return 1;
            }
        }
    return 0;
}
int main() {
    while (scanf("%d%d",&n,&m)!=EOF) {
        for (int i=1;i<=n;i++) p[i]=head[i]=0;
        cnt=0;
        for (int i=1;i<=n;i++) {
            int x;scanf("%d",&x);
            for (int j=1;j<=x;j++) {
                int t;scanf("%d",&t);
                insert(i,t);
            }
        }
        int ans=0;
        for (int i=1;i<=n;i++) {
            for (int j=1;j<=n;j++) vis[j]=0;
            if (find(i)) ans++;
        }
        printf("%d\n",ans);
    }
    return 0;
}