poj 1469 COURSES 【匈牙利匹配】

题目链接:​​http://poj.org/problem?id=1469​​​
题意：最大匹配学生与课程数。
解法：ans == 学生数量 YES else NO
代码：

#include <stdio.h>
#include <ctime>
#include <math.h>
#include <limits.h>
#include <complex>
#include <string>
#include <functional>
#include <iterator>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <list>
#include <bitset>
#include <sstream>
#include <iomanip>
#include <fstream>
#include <iostream>
#include <ctime>
#include <cmath>
#include <cstring>
#include <cstdio>
#include <time.h>
#include <ctype.h>
#include <string.h>
#include <assert.h>

using namespace std;

int n, m, num, k;
int p[310][310];
int book[310];
int match[310];
int t;
bool vis[310];

bool dfs(int u)
{
    int i;
    for (i = 1; i <= m; i++)
    {
        if (book[i] == 0 && p[u][i] == 1)
        {
            book[i] = 1;
            if (match[i] == 0 || dfs(match[i]))
            {
                match[i] = u;
                return true;
            }
        }
    }
    return false;
}


int main()
{
    scanf("%d",&t);
    while (t--)
    {
        memset(p, 0, sizeof(p));
        memset(match, 0, sizeof(match));
        memset(vis,false,sizeof(vis));

        scanf("%d%d",&n,&m);

        for (int i = 1; i <= n; i++)
        {
            scanf("%d",&num);
            for (int j = 1; j <= num; j++)
            {
                scanf("%d",&k);
                p[i][k] = 1;
                //p[num][m] = 1;
            }
        }

        int ans = 0;
        for (int i = 1; i <= n; i++)
        {
            memset(book, 0, sizeof(book));
            if (dfs(i))
                ans++;
        }
        if (ans == n) puts("YES");
        else puts("NO");
    }
    return 0;
}