Lake Counting(DFS连通图)

Description

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

Hint

OUTPUT DETAILS:

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

题目意思：查找所有由w组成的区域，八面搜索，只要周围有w就能连接在一起组成一个区域。

解题思路：这是一道很基本的深搜例题，当成模板直接来使用吧。

上代码：

 #include<stdio.h>

 #include<string.h>

 #include<algorithm>

 #include<iostream>

 using namespace std;

 char map[][];

 int vis[][];///标记数组

 int dir[][]={{,},{-,},{,},{,-},{,},{-,-},{,-},{-,}};

 int n,m;

 void DFS(int x,int y)

 {

     int a,b,i;

     vis[x][y]=;

     for(i=;i<;i++)

     {

         a=x+dir[i][];

         b=y+dir[i][];

         if(a>=&&a<n&&b>=&&b<m&&vis[a][b]==&&map[a][b]=='W')

         {

             DFS(a,b);

         }

     }

         return ;

 }

 int main()

 {

     int count,i,j;

     memset(map,,sizeof(map));

     memset(vis,,sizeof(vis));

     scanf("%d%d",&n,&m);

     getchar();

     count=;

     for(i=;i<n;i++)

     {

         scanf("%s",map[i]);

     }

     for(i=;i<n;i++)

     {

         for(j=;j<m;j++)

         {

             if(vis[i][j]==&&map[i][j]=='W')

             {

                 count++;

                 DFS(i,j);

             }

         }

     }

     printf("%d\n",count);

     return ;

 }

巴特西

Lake Counting(DFS连通图)

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