Number of Islands

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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:

Answer: 1

Example 2:

Answer: 3

与上一题的解决思路是类似的，如果是1，上下左右遍历，是1则置为0.

public class Solution {    public int numIslands(char[][] grid) {if(grid==null||grid.length<=0)return 0;int count=0;for(int i=0;i<grid.length;i++){for(int j=0;j<grid[0].length;j++){if(grid[i][j]=='1'){count++;find(grid,i,j);}}}return count;}private void find(char[][] grid,int i,int j){if(i<0||j<0||i>=grid.length||j>=grid[0].length)return;if(grid[i][j]!='1')return;grid[i][j]='0';find(grid,i+1,j);find(grid,i-1,j);find(grid,i,j-1);find(grid,i,j+1);}}

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