HDU 1281 棋盘游戏

题解：将所有的横坐标看作一边的点，纵坐标看作另一边的点，然后二分图匹配即可，建图很巧妙……

#include <cstdio> 
#include <cstring> 
#define maxn 105  
bool map[maxn][maxn],vis[maxn];  
int n,m,k,mark[maxn],edge[maxn*maxn][2];  
bool dfs(int v){  
    for(int i=1;i<=m;i++){  
        if(vis[i]||!map[i][v])  
            continue;  
        vis[i]=true;  
        if(mark[i]==0||dfs(mark[i])){  
            mark[i]=v;  
            return true;  
        }  
    }  
    return false;  
}    
int Hungarian(){
    int count=0;  
    memset(mark,0,sizeof(mark));  
    for(int i=1; i<=n; i++){  
        memset(vis,false,sizeof(vis));  
        if(dfs(i)) count++;  
    }  
    return count;  
}  
int main(){  
    int i,sum,num=1;  
    while(scanf("%d%d%d",&n,&m,&k)!=EOF){  
        memset(map,false,sizeof(map));  
        for(i=0;i<k;i++){  
            scanf("%d%d",&edge[i][0],&edge[i][1]);  
            map[edge[i][0]][edge[i][1]] = true;  
        }  
        int max=Hungarian();   
        for(i=sum=0;i<k;i++){  
            map[edge[i][0]][edge[i][1]]=false;  
            if(max>Hungarian()) sum++;  
            map[edge[i][0]][edge[i][1]]=true;  
        }  
        printf("Board %d have %d important blanks for %d chessmen.\n",num++,sum,max);  
    }  
    return 0;  
}