HDU-1281 棋盘游戏 二分图匹配匈牙利算法

中文题，题目不用多说，先求出最大匹配，然后依次把每条边剪短，再取最大匹配，如果比最初的匹配值小，num++

#include <iostream>#include <cmath>#include <cstring>#include <algorithm>#include <queue>#include <cstdio>#include <cstdlib>using namespace std;const int maxn=111;int map[maxn][maxn];int link[maxn];int visit[maxn];int n,m,p;bool dfs(int k){for(int i=1;i<=m;i++){if(!visit[i]&&map[k][i]){visit[i]=1;int j=link[i];if(j==-1||dfs(j)){link[i]=k;return true;}}}return false;}int hungary(){int num=0;memset(link,-1,sizeof(link));//初始化 for(int i=1;i<=n;i++){memset(visit,0,sizeof(visit));if(dfs(i))//有增广路 {num++;//匹配数++ }}return num;}int main(){int x,y;int ans;int t=1;int num;while(scanf("%d%d%d",&n,&m,&p)!=EOF){memset(map,0,sizeof(map));for(int i=0;i<p;i++){scanf("%d %d",&x,&y);map[x][y]=1;}ans=hungary();//cout<<ans<<endl;num=0;for(int i=1;i<=n;i++){for(int j=1;j<=m;j++){if(map[i][j]==1){map[i][j]=0;if(hungary()<ans){num++;}map[i][j]=1;}}}printf("Board %d have %d important blanks for %d chessmen.\n",t++,num,ans);  }return 0;}