HDU 1312 Red and Black

 

http://acm.hdu.edu.cn/showproblem.php?pid=1312

从这老题开始吧

#include <iostream>
#include <queue>
using namespace std ;
char map[25][25];
int ans,n,m;
typedef struct L{
    int x,y;
}L;
void bfs(int x,int y)
{
    queue <L> q ;
    int tab[][2]={1,0,-1,0,0,1,0,-1};
    L point,go,front;
    point.x=x;
    point.y=y;
    q.push(point);
    map[x][y]='#';
    while(!q.empty())
    {
        front=q.front();
        q.pop();
        for(int i=0;i<4;i++)
        {
            go.x=front.x+tab[i][0];
            go.y=front.y+tab[i][1];
            if(go.x>=0&&go.x<n&&go.y>=0&&go.y<m&&map[go.x][go.y]=='.')
            {
                ans++;
                q.push(go);
                map[go.x][go.y]='#';
            }
        }
    }
}
int main()
{
    while(scanf("%d%d",&m,&n),(m||n))
    {
        for(int i=0;i<n;i++)
            scanf("%s",map[i]);
        int x,y;
        for(int i=0;i<n;i++)
            for(int j=0;j<m;j++)
                if(map[i][j]=='@')
                    x=i,y=j;
        ans=1;
        bfs(x,y);
        printf("%d\n",ans);
    }
    return 0;
}