hdu 4185Oil Skimming （二分匹配）

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赤裸裸的二分匹配。。。

#include"stdio.h"#include"string.h"#define N 601int map[N][N],v[N],link[N],a[N][N];char str[N][N];int n;int dfs(int k){int i;for(i=0;i<n;i++){if(map[k][i]&&!v[i]){v[i]=1;if(link[i]==-1||dfs(link[i])){link[i]=k;return 1;}}}return 0;}int main(){int i,j,t,ans,tt,cnt;scanf("%d",&t);tt=0;while(t--){scanf("%d",&n);cnt=0;memset(a,0,sizeof(a));for(i=0;i<n;i++){scanf("%s",str[i]);for(j=0;j<n;j++)if(str[i][j]=='#')a[i][j]=cnt++;}memset(map,0,sizeof(map));for(i=0;i<n;i++){for(j=0;j<n;j++){if(str[i][j]=='#'){if(i>0&&str[i-1][j]=='#')map[a[i][j]][a[i-1][j]]=1;if(i<n-1&&str[i+1][j]=='#')map[a[i][j]][a[i+1][j]]=1;if(j>0&&str[i][j-1]=='#')map[a[i][j]][a[i][j-1]]=1;if(j<n-1&&str[i][j+1]=='#')map[a[i][j]][a[i][j+1]]=1;}}}n=cnt;memset(link,-1,sizeof(link));ans=0;for(i=0;i<n;i++){memset(v,0,sizeof(v));if(dfs(i))ans++;}printf("Case %d: %d\n",++tt,ans/2);}return 0;}