bzoj 1191: [HNOI2006]超级英雄Hero

一开始还以为用2-SAT。。

愣了几分钟才发现是二分图匹配，

用匈牙利算法找匹配碰到一个不能匹配的就退出就可以了。

/*
ID:WULALA
PROB:bzoj1191 
LANG:C++
*/
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <iostream>
#include <ctime>
#include <set>
#define N 1008
#define M 1008
#define mod
#define mid(l,r) ((l+r) >> 1)
#define INF 0x7ffffff
using namespace std;

int n,m,tot,Link[M],ans,head[N],vis[M];

struct WULALA
{
    int node,next;
}e[2 * N];

bool find(int a)
{
    int c = head[a];
    for (;c;c =e[c].next)
        if (!vis[e[c].node])
        {
            vis[e[c].node] = true;
            if (Link[e[c].node] == -1 || find(Link[e[c].node]))
            {
                Link[e[c].node] = a;
                return true;
            }
        }
    return false;
}

int main()
{
    scanf("%d%d",&m,&n);
    memset(Link,255,sizeof(Link));
    for (int i = 1;i <= n;i++)
    {
        int a,b;
        scanf("%d%d",&a,&b);
        e[++tot].node = a;
        e[tot].next = head[i];
        head[i] = tot;
        e[++tot].node = b;
        e[tot].next = head[i];
        head[i] = tot;
    }
    for (int i = 1;i <= n;i++)
    {
        memset(vis,0,sizeof(vis));
        if (find(i)) ans++;
        else break;
    }
    printf("%d
",ans);
    return 0;
}