DFS + 染色版本

  1. function numIslands(grid) {
  2.     if (!Array.isArray(grid)) {
  3.         return 0;
  4.     }
  5.     if (!Array.isArray(grid[0])) {
  6.         return 0;
  7.     }
  8.     let landNum = 0;
  10.     for (let i = 0; i < grid.length; i++) {
  11.         for (let j = 0; j < grid[0].length; j++) {
  12.             if (grid[i][j] === '1') {
  13.                 landNum++;
  14.                 dfs(grid, i, j)
  15.             }
  16.         }
  17.     }
  18.     return landNum;
  19. }
  22. function dfs(grid, i, j) {
  23.     let m = grid.length;
  24.     let n = grid[0].length;
  26.     let direction = [
  27.         [0, 1],
  28.         [0, -1],
  29.         [1, 0],
  30.         [-1, 0]
  31.     ];
  32.     if (i < 0 || i >= m || j < 0 || j >= n || grid[i][j] != '1') {
  33.         return;
  34.     }
  35.     grid[i][j] = '0';
  36.     for (let d = 0; d < direction.length; d++) {
  37.         dfs(grid, i + direction[d][0], j + direction[d][1]);
  38.     }
  39. }