题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=1281

根据题目描述，什么是重要点？在求出最大匹配后，进行枚举，依次删边，看最大匹配数会不会发生改变，改变的话，那么该点就是重要点。

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <math.h>
#define init(a) memset(a,0,sizeof(a))
#define PI acos(-1,0)
using namespace std;
const int maxn = 110;
const int maxm = 10100;
#define lson left, m, id<<1
#define rson m+1, right, id<<1|1
#define min(a,b) (a>b)?b:a
#define max(a,b) (a>b)?a:b
int mar[maxn][maxn];
int G[maxn][maxn];
int line[maxn];
bool vis[maxn];
int n,m,k;
int DFS(int u)
{
    for(int v = 1;v<=m;v++)
    {
        if(G[u][v] && !vis[v])
        {
            vis[v] = 1;
            if(line[v] == -1 || DFS(line[v]))
            {
                line[v] = u;
                return 1;
            }
        }
    }
    return 0;
}

int K_M()
{
    int ans = 0;
    memset(line,-1,sizeof(line));
    for(int i = 1;i<=n;i++)
    {
        init(vis);
        ans += DFS(i);
    }
    return ans;
}
int main()
{
    int x[maxm],y[maxm],C = 0;
    while(scanf("%d%d%d",&n,&m,&k)!=EOF)
    {
        C++;
        init(G);
        for(int i = 1;i<=k;i++)
        {
            scanf("%d%d",&x[i],&y[i]);
            G[x[i]][y[i]] = 1;
        }
        int ans = K_M();
        int num = 0;
        for(int i = 1;i<=k;i++)
        {
            G[x[i]][y[i]] = 0;//删边
            if(ans > K_M()) num++;
            G[x[i]][y[i]] = 1;//恢复
        }
        printf("Board %d have %d important blanks for %d chessmen.\n",C,num,ans);
    }
    return 0;
}