poj3020

define     n    the number of  ' * '

define     d    the number of couple of two points

define     s    the single point that can't link to others ( means no points around it in 4 directions )

n = 2 * d + s ;

d + s = n - d

use Hungary finding out the d

 #include <stdio.h>
 #include <string.h>
 char gird[][];
 int number[][];
 int graph[][];
 int in[];
 int already[];
 int cnt;

 struct node{
     int x,y;
 }p[];
 int dir[][]={ ,,,-,-,,,};

 int find(int a){
     int i;
     for(i=;i<cnt;++i){
         if( graph[a][i]== && in[i]== ){
             in[i]=;
             if( already[i]==- || find( already[i] )){
                 already[i]=a;
                 return ;
             }
         }
     }
     return ;
 }

 int main(){
     int t;
     int n,m,i,j;
     int tx,ty,tnum;
     int res;
     while(~scanf("%d",&t)){
         while(t--){
             res=;
             cnt=;
             memset(in,,sizeof(in));
             memset(graph,,sizeof(graph));
             for(i=;i<;++i)    already[i]=-;
             scanf("%d%d",&n,&m);
             for(i=;i<n;++i){
                 scanf("%s",gird[i]);
                 for(j=;j<m;++j)
                     if(gird[i][j]=='*'){
                         number[i][j]=cnt;
                         p[cnt].x=i;
                         p[cnt].y=j;
                         cnt++;
                     }
             }
             for(i=;i<cnt;++i){
                 for(j=;j<;++j){
                     tx=p[i].x+dir[j][];
                     ty=p[i].y+dir[j][];
                     if((!(tx>=&&tx<n&&ty>=&&ty<m))||gird[tx][ty]!='*')    continue;
                     tnum=number[tx][ty];
                     graph[i][tnum]=;
                 }
             }
             for(i=;i<cnt;++i){
                 memset(in,,sizeof(in));
                 if(find(i)==)
                     res++;
             }
             printf("%d\n",cnt-res/);
         }
     }
     return ;
 }