hdu4185 Oil Skimming (最大匹配)

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题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=4185

题解：水平和竖直方向;有#相邻,连一条边，求最大匹配。

#include <cstdio>    #include <cstring>    #include <vector>    #define MAXN 602 #define MAXV 1000using namespace std;    vector<int> mp[MAXN];    int from[MAXV],visited[MAXV];  int matr[MAXN][MAXN];char gra[MAXN][MAXN];int match(int x)  {  int i,temp,size;  size=mp[x].size();  for(i=0;i<size;++i)  {  temp=mp[x][i];  if(!visited[temp])  {  visited[temp]=1;  if(from[temp]==-1||match(from[temp]))  {  from[temp]=x;  return 1;  }  }  }  return 0;  }  int hungary(int n){int i,sum=0;memset(from,-1,sizeof(from));for(i=0;i<n;++i){memset(visited,0,sizeof(visited));if(match(i))++sum;}return sum;}int main(){int n,test,i,j,cnt,cases=0;scanf("%d",&test);while(test--){scanf("%d",&n);cnt=0;for(i=0;i<n;++i){scanf("%s",gra[i]);for(j=0;j<n;++j){if(gra[i][j]=='#')matr[i][j]=cnt++;}}for(i=0;i<=cnt;++i){mp[i].clear();}for(i=0;i<n;++i){for(j=0;j<n;++j){if(gra[i][j]!='#')continue;if(i>0&&gra[i-1][j]=='#')mp[matr[i][j]].push_back(matr[i-1][j]);if(i<n-1&&gra[i+1][j]=='#')mp[matr[i][j]].push_back(matr[i+1][j]);if(j>0&&gra[i][j-1]=='#')mp[matr[i][j]].push_back(matr[i][j-1]);if(j<n-1&&gra[i][j+1]=='#')mp[matr[i][j]].push_back(matr[i][j+1]);}}n=cnt;cnt=hungary(n);printf("Case %d: %d\n",++cases,cnt/2);}return 0;}