200. 岛屿数量

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  1. class Solution {
  2.     private int count;
  3.     private int[][] direc = {{0, 1}, {1, 0}, {-1, 0}, {0, -1}};
  4.     public int numIslands(char[][] grid) {
  5.         if (grid == null || grid.length == 0 || grid[0].length == 0) return 0;
  6.         int m = grid.length, n = grid[0].length;
  7.         for (int i = 0; i < m; i++) {
  8.             for (int j = 0; j < n; j++) {
  9.                 if (grid[i][j] == '1') {
  10.                     count++;
  11.                     fill(grid, i, j);
  12.                 }
  13.             }
  14.         }
  15.         return count;
  16.     }
  17.     private void fill(char[][] grid, int x, int y) {
  18.         if (x < 0 || y < 0 || x == grid.length || y == grid[0].length) return;
  19.         if (grid[x][y] != '1') return;
  21.         grid[x][y] = '#';
  22.         for (int i = 0; i < 4; i++) {
  23.             int nextX = x + direc[i][0];
  24.             int nextY = y + direc[i][1];
  25.             fill(grid, nextX, nextY);
  26.         }
  27.     }
  28. }