200. Number of Islands

Leetcode Union Find Depth-First Search Breath-First Search

Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by water.

Example 1:

Input:

11110
11010
11000
00000

Output: 1

Example 2:

Input:

11000
11000
00100
00011

Output: 3

分析

这道题目其实和Q130. Surrounded Regions一摸一样，换汤不换药，把字母O换成了1，仅此而已。省略吧，不写了。