NOI2.5-1388Lake Counting
3302+

## 题目描述

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.

## 输入

* 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.

## 输出

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

## 样例输入

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

## 样例输出

3

# 解题思路

Flood Fill算法，地图填充，遍历整个地图，遇到W，累加湖数，并填成非W，搜索该湖其他W，都填成非W；后面搜索只搜索W的，就不会重复搜索。深搜和广搜都可以，时间复杂度O(n*m)。