poj 2386 Lake Counting

 

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <stack>
#define Max 101
using namespace std;
char mp[Max][Max];
int n,m,vis[Max][Max],c;
int dir[8][2] = {0,1,1,0,0,-1,-1,0,1,1,1,-1,-1,1,-1,-1};
void dfs(int x,int y)
{
    for(int i = 0;i < 8;i ++)
    {
        int tx = x + dir[i][0];
        int ty = y + dir[i][1];
        if(tx < 0 || ty < 0 || tx >= n || ty >= m || mp[tx][ty] == '.' || vis[tx][ty])continue;
        vis[tx][ty] = 1;
        dfs(tx,ty);
    }
}
int main()
{
    cin>>n>>m;
    for(int i = 0;i < n;i ++)
        cin>>mp[i];
    for(int i = 0;i < n;i ++)
    {
        for(int j = 0;j < m;j ++)
        {
            if(mp[i][j] == 'W' && vis[i][j] == 0)
            {
                vis[i][j] = 1;
                dfs(i,j);
                c ++;
            }
        }
    }
    cout<<c<<endl;
}

Due to recent rains, water has pooled in various places in Farmer John's field, which is represented by a rectangle of N x M (1 <= N <= 100; 1 <= M <= 100) squares. Each square contains either water ('W') or dry land ('.'). Farmer John would like to figure out how many ponds have formed in his field. A pond is a connected set of squares with water in them, where a square is considered adjacent to all eight of its neighbors.

Given a diagram of Farmer John's field, determine how many ponds he has.

Input

* Line 1: Two space-separated integers: N and M

* Lines 2..N+1: M characters per line representing one row of Farmer John's field. Each character is either 'W' or '.'. The characters do not have spaces between them.

Output

* Line 1: The number of ponds in Farmer John's field.

Sample Input

10 12
W........WW.
.WWW.....WWW
....WW...WW.
.........WW.
.........W..
..W......W..
.W.W.....WW.
W.W.W.....W.
.W.W......W.
..W.......W.

Sample Output

3

Hint

OUTPUT DETAILS:

There are three ponds: one in the upper left, one in the lower left,and one along the right side.

Source

USACO 2004 November

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 42151		Accepted: 20899