HDU-1312 Red and Black

/************************************************
* Author        :somniloquy
* Created Time  :2015/10/30 13:23:15
************************************************/

#include <cstdio>
#include <algorithm>
#include <iostream>
#include <cstring>

using namespace std;

const int wh_max = 20 + 5;
int w, h;
char graph[wh_max][wh_max];
int sign[wh_max][wh_max];
struct node
{
int x;
int y;
} start;
int ans;
int dx[4] = {-1, 1, 0, 0};
int dy[4] = {0, 0, -1, 1};

void dfs(node now)
{
for(int i = 0; i < 4; i ++)
{
node next = now;
next.x += dx[i];
next.y += dy[i];
if(next.x >= 0 && next.x < h && next.y >= 0 && next.y < w &&graph[next.x][next.y] != '#' && !sign[next.x][next.y])
{
sign[next.x][next.y] = 1;
ans ++;
dfs(next);
}
}
return;
}

int main(void)
{
while(~scanf("%d %d", & w, & h))
{
getchar();
if(!w && !h)
break;
memset(sign, 0, sizeof(sign));
for(int i = 0; i < h; i ++)
{
for(int j = 0; j < w; j ++)
{
scanf("%c", & graph[i][j]);
if(graph[i][j] == '@')
{
start.x = i;
start.y = j;
ans = 1;
sign[i][j] = 1;
}
}
getchar();
}
dfs(start);
printf("%d\n", ans);
}
return 0;
}