Light OJ 1012

#include<bits/stdc++.h>
using namespace std;
const int maxn = 20 + 13;
const int step[4][2] = {0,1,0,-1,1,0,-1,0};
bool Vis[maxn][maxn];
char Map[maxn][maxn];
int Num, N, M;

void BFS(int x, int y)
{
    Vis[x][y] = true;
    Num = 1;
    pair<int,int> Begin = make_pair(x, y);
    queue<pair<int,int> > Q;
    Q.push(Begin);
    while(!Q.empty())
    {
        pair<int,int> tmp = Q.front();
        Q.pop();
        for(int i = 0; i < 4; ++i)
        {
            int xx = tmp.first + step[i][0];
            int yy = tmp.second + step[i][1];
            if(xx < 0 || xx >= N || yy < 0 || yy >= M || Vis[xx][yy])
                continue ;
            if(Map[xx][yy] == ‘#‘) continue ;
            Num++;
            Vis[xx][yy] = true;
            Q.push(make_pair(xx, yy));
        }
    }
}

int main()
{
    int t;
    scanf("%d",&t);
    for(int kase = 1; kase <= t; ++kase)
    {
        scanf("%d %d",&M, &N);
        memset(Vis, 0, sizeof(Vis));
        int x, y;
        for(int i = 0; i < N; ++i)
        {
            scanf("%s",Map[i]);
            for(int j = 0; j < M; ++j)
            {
                if(Map[i][j] == ‘@‘)
                {
                    x = i, y = j;
                }
            }
        }
        BFS(x, y);
        printf("Case %d: %d\n",kase, Num);
    }
}