北大ACM poj1979 Red and Black

#include<stdio.h>

char map[21][21];
int c;
int n,m;
void count(char map[21][21],int i,int j){
    map[i][j]='#';
    if(i+1< m&&map[i+1][j]=='.'){
        c++;
        count(map,i+1,j);
    }
    if(i-1>-1&&map[i-1][j]=='.'){
        c++;
        count(map,i-1,j);
    }
    if(j+1<n&&map[i][j+1]=='.'){
        c++;
        count(map,i,j+1);
    }
    if(j-1>-1&&map[i][j-1]=='.'){
        c++;
        count(map,i,j-1);
    }
}
int main(){

    int i,j;
    //freopen("in.txt","r",stdin);
    while(scanf("%d%d",&n,&m)&&n){
        for(i=0;i<m;i++){
            scanf("%s",map[i]);
        }
        for(i=0;i<m;i++){
            for(j=0;j<n;j++){
                if(map[i][j]=='@'){
                    c=1;
                    count(map,i,j);
                    printf("%d\n",c);
                }

            }
        }
    }
}