POJ 2386 Lake Counting
简单的DFS，用了stack代替递归，输入有问题，搞了蛮久，算法是没问题。所以以后一定要记得加上检查输入的那一步
然后对于点的定义以后就这么办吧
此外还有stack的用法，也可以这样

//POJ 2386
#include <cstdio>
#include <stack>
using namespace std;
class Point
{
public:
    Point(int xx, int yy)
    {
        x=xx;
        y=yy;
    }
    int x, y;
};
int main()
{
    int n, m, ans=0;
    scanf("%d%d", &n, &m);
    const int maxn = 200, maxm = 200;
    char g[maxn][maxm];
    for (int i=0;i<n;i++)
    {
        scanf("\n");
        for (int j=0;j<m;j++)
            scanf("%c", &g[i][j]);
    }
    stack<Point> s;
    for (int i=0;i<n;i++)
        for (int j=0;j<m;j++)
        if (g[i][j]=='W')
        {
            g[i][j] = '.';
            s.push(Point(i, j));
            while (s.size())
            {
                Point p = s.top();
                s.pop();
                for (int dx=-1;dx<2;dx++)
                {
                    for (int dy=-1;dy<2;dy++)
                    {
                        int nx = p.x+dx, ny = p.y+dy;
                        if (nx<0||ny<0||nx>=n||ny>=m) continue;
                        if (g[nx][ny]=='W')
                        {
                            g[nx][ny] = '.';
                            s.push(Point(nx, ny));
                        }
                    }
                }
            }
            ans++;
        }
    printf("%d\n", ans);
    return 0;
}