POJ 1979 Red and Black (简单dfs)

题目：

简单dfs，没什么好说的

代码：

#include <iostream>
using namespace std;
typedef long long ll;
#define INF 2147483647

int w,h;
char a[22][22];
int dir[4][2] = {-1,0,1,0,0,-1,0,1};
int ans = 0;

void dfs(int x,int y){
    if(x < 0 || x >= h || y < 0 || y >= w || a[x][y] == '#') return;
    ans++;
    a[x][y] = '#';
    for(int i = 0;i < 4; i++){
        dfs(x+dir[i][0],y+dir[i][1]);
    }
}

int main(){
    while(cin >> w >> h){
        if(w == 0 && h == 0) break;
        ans = 0;
        int sx,sy;
        for(int i = 0;i < h; i++){
            for(int j = 0;j < w; j++){
                cin >> a[i][j];
                if(a[i][j] == '@'){
                    sx = i;sy = j;
                }
            }
        }
        dfs(sx,sy);
        cout << ans << endl;
    }
    return 0;
}