HDU 1312 Red and Black （第一道广搜）

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

大意：从@出发，只能站在不能站在#上。。。。求能踩到的.的个数（包括起始点@）

#include <set>
#include <map>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <cstdio>
#include <string>
#include <vector>
#include <cctype>
#include <cstring>
#include <sstream>
#include <fstream>
#include <cstdlib>
#include <cassert>
#include <iostream>
#include <algorithm>
 
using namespace std;
//Constant Declaration
/*--------------------------*/
//#define LL long long 
#define LL __int64
const int M = 100;
const int INF = 1<<30;
const double EPS = 1e-11;
const double PI = acos(-1.0);
/*--------------------------*/
// some essential funtion
/*----------------------------------*/
void Swap(int &a,int &b){   int t=a;a=b;b=t; }
int Max(int a,int b){   return a>b?a:b;  }
int Min(int a,int b){   return a<b?a:b;  }
int Gcd(int a,int b){   while(b){b ^= a ^=b ^= a %= b;}  return a; }
/*----------------------------------*/
//for (i = 0; i < n; i++)
/*----------------------------------*/
 

char g[M][M];
int to[4][2] = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
int n, m;

struct Point
{
    int x, y;
};

int Bfs(int x, int y)
{
    int sum = 1;
    int i;
    queue <Point> Q;
    Point a, front, go;
    a.x = x;
    a.y = y;
    Q.push(a);
    g[x][y] = '#';
    while (!Q.empty())
    {
        front = Q.front();
        Q.pop();
        for (i = 0; i < 4; i++)
        {
            go.x = front.x + to[i][0];
            go.y = front.y + to[i][1];
            if (go.x>=0 && go.x<n && go.y>=0 && go.y<m && g[go.x][go.y] == '.')
            {
                sum++;
                Q.push(go);
                g[go.x][go.y] = '#';//关键
            }
        }
    }
    return sum;
}


int main()
{
 //freopen("in.txt","r",stdin);
 //freopen("out.txt","w",stdout);
 //int t, case1 = 0;
 //scanf("%d", &t);
 
 int i, j;
 int x, y;
 while (scanf("%d%d", &m, &n), n+m)
 {
     for (i = 0; i < n; i++)
     {
         for (j = 0; j < m; j++)
         {
             scanf(" %c", &g[i][j]);
             if (g[i][j] == '@')
             {
                 x = i;
                 y = j;
             }
         }
     }
     printf("%d\n", Bfs(x, y));
 }
 
 return 0;
}