poj 2239 Selecting Courses

二分图基础。

求二分图最大匹配（匈牙利算法）。

/*
Author:Zhaofa Fang
Lang:C++
*/
#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <cmath>
#include <cstring>
#include <algorithm>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>
#define pb push_back
using namespace std;

//==========================================
//二分图最大匹配

const int maxn=305;
bool maz[maxn][maxn],vist[maxn];
int match[maxn],n,m;

bool dfs(int u)
{
    for(int v=1;v<=m;v++)
    {
        if(maz[u][v] && !vist[v])
        {
            vist[v]=true;
            if(match[v] == -1 || dfs(match[v]))
            {
                match[v]=u;
                return true;
            }
        }
    }
    return false;
}

int Match()
{
    int cnt=0;
    memset(match,-1,sizeof(match));
    for(int u=1;u<=n;u++)
    {
        memset(vist,false,sizeof(vist));
        if(dfs(u))cnt++;
    }
    return cnt;
}

int main()
{
    while(~scanf("%d",&n))
    {
        memset(maz,0,sizeof(maz));
        m=0;
        for(int i=1;i<=n;i++)
        {
            int t;
            scanf("%d",&t);
            while(t--)
            {
                int q,p;
                scanf("%d%d",&q,&p);
                maz[i][q*12+p]=true;
                m=max(m,q*12+p);
            }
        }
        printf("%d\n",Match());
    }
    return 0;
}