岛屿数量

https://leetcode-cn.com/problems/number-of-islands/

  1. class Solution {
  3.     int r;
  4.     int c;
  5.     int count = 0;
  7.     public int numIslands(char[][] grid) {
  8.         if(grid == null)
  9.             return 0;
  10.         r = grid.length;
  11.         c = grid[0].length;
  12.         for(int i = 0; i < r; i++){
  13.             for(int j = 0; j < c; j++){
  14.                 if(grid[i][j] == '1'){
  15.                     count++;
  16.                     dfs(grid, i, j);
  17.                 }
  18.             }
  19.         }
  20.         return count;
  21.     }
  23.     public void dfs(char[][] grid, int x, int y){
  25.         if(x < 0 || y < 0 || x >= r || y>=c || grid[x][y] == '0')
  26.             return;
  27.         grid[x][y] = '0';
  28.         dfs(grid, x + 1, y);
  29.         dfs(grid, x, y + 1);
  30.         dfs(grid, x - 1, y);
  31.         dfs(grid, x, y - 1);
  32.     }
  33. }