hdu 1312

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

题意：找可以到达的黑格子。

mark：dfs..

代码：

#include <stdio.h>

char a[25][25];
int sum;

void ss(int w, int h, int x, int y)
{
    if(y > 0 && a[x][y-1] == '.')
    {
        a[x][y-1] = '1';
        sum++;
        ss(w, h, x, y-1);
    }
    if(x < h-1 && a[x+1][y] == '.')
    {
        a[x+1][y] = '1';
        sum++;
        ss(w, h, x+1, y);
    }
    if(y < w-1 && a[x][y+1] == '.')
    {
        a[x][y+1] = '1';
        sum++;
        ss(w, h, x, y+1);
    }
    if(x > 0 && a[x-1][y] == '.')
    {
        a[x-1][y] = '1';
        sum++;
        ss(w, h, x-1, y);
    }
    return ;
}

int main()
{
    int w,h;
    int i,j,f,x,y;
    while(scanf("%d%d", &w, &h), w+h)
    {
        for(i = 0; i < h; i++)
            scanf("%s", a[i]);
        for(i = f = 0; i < h; i++)
        {
            if(f) break;
            for(j = 0; j < w; j++)
                if(a[i][j] == '@') {f = 1, x = i, y = j; break;}
        }
        a[x][y] = '1';
        sum = 1;
        ss(w, h, x, y);
        printf("%d\n", sum);
    }
    return 0;
}