学步园

题目：题目链接

题意：给你N头牛，在给出每头牛愿意产奶的产房号，问你最后有多少头奶牛可以顺利产奶

分析：二分图的最大匹配，对于每一头牛对号入座匹配。牛和房连号，求最大匹配

代码：

#include <iostream>
#include <cstdio>
#include <string>
#include <string.h>
#include <map>
#include <vector>
#include <cstdlib>
#include <algorithm>
#include <cmath>
#include <queue>
#include <set>
#include <stack>
#include <functional>
#include <fstream>
#include <sstream>
#include <iomanip>
#include <numeric>
#include <cassert>
#include <bitset>
#include <stack>
#include <ctime>
#include <list>
#define INF 0x7fffffff
#define max3(a,b,c) (max(a,b)>c?max(a,b):c)
#define min3(a,b,c) (min(a,b)<c?min(a,b):c)
#define mem(a,b) memset(a,b,sizeof(a))
using namespace std;
#define maxn 205
int QuickMod(int  a,int b,int n)
{
    int r = 1;
    while(b)
    {
        if(b&1)
            r = (r*a)%n;
        a = (a*a)%n;
        b >>= 1;
    }
    return r;
}
int mp[maxn][maxn];
int link[maxn];
int vis[maxn];
int n, m;
int find(int x)
{
    for(int i = 1; i <= m; ++i)
    {
        if(mp[x][i] && !vis[i])
        {
            vis[i] = 1;
            int tp = link[i];
            link[i] = x;
            if(tp == -1 || find(tp))return true;
            link[i] = tp;
        }
    }
    return false;
}
int solve()
{
    int ans = 0;
    mem(link, -1);
    for(int i = 1; i<=n; ++i)
    {
        mem(vis, 0);
        if(find(i))
            ans++;
    }
    return ans;
}
int main()
{

    while(scanf("%d%d", &n, &m) == 2)
    {
        int np;
        mem(mp, 0);
        for(int i = 1; i <= n; ++i)
        {
            scanf("%d", &np);
            int tp;
            for(int j = 1; j <= np; ++j)
            {
                scanf("%d", &tp);
                mp[i][tp] = 1;
            }
        }
        int ans = solve();
        printf("%d\n", ans);
    }
    return 0;
}