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[50][25];
int number[50][25];
int graph[1000][1000];
int in[1000];
int already[1000];
int cnt;

struct node{
    int x,y;
}p[1000];
int dir[4][2]={ 0,1,0,-1,-1,0,1,0};

int find(int a){
    int i;
    for(i=0;i<cnt;++i){
        if( graph[a][i]==1 && in[i]==0 ){
            in[i]=1;
            if( already[i]==-1 || find( already[i] )){
                already[i]=a;
                return 1;
            }
        }
    }
    return 0;
}

int main(){
    int t;
    int n,m,i,j;
    int tx,ty,tnum;
    int res;
    while(~scanf("%d",&t)){
        while(t--){
            res=0;
            cnt=0;
            memset(in,0,sizeof(in));
            memset(graph,0,sizeof(graph));
            for(i=0;i<1000;++i)    already[i]=-1;
            scanf("%d%d",&n,&m);
            for(i=0;i<n;++i){
                scanf("%s",gird[i]);
                for(j=0;j<m;++j)
                    if(gird[i][j]=='*'){
                        number[i][j]=cnt;
                        p[cnt].x=i;
                        p[cnt].y=j;
                        cnt++;
                    }
            }
            for(i=0;i<cnt;++i){
                for(j=0;j<4;++j){
                    tx=p[i].x+dir[j][0];
                    ty=p[i].y+dir[j][1];
                    if((!(tx>=0&&tx<n&&ty>=0&&ty<m))||gird[tx][ty]!='*')    continue;
                    tnum=number[tx][ty];
                    graph[i][tnum]=1;
                }
            }
            for(i=0;i<cnt;++i){
                memset(in,0,sizeof(in));
                if(find(i)==1)
                    res++;
            }
            printf("%d
",cnt-res/2);
        }
    }
    return 0;
}