| 3 | // Definition for a binary tree node. |
| 4 | |
| 5 | public class TreeNode { |
| 6 | int val; |
| 7 | TreeNode left; |
| 8 | TreeNode right; |
| 9 | TreeNode() {} |
| 10 | TreeNode(int val) { this.val = val; } |
| 11 | TreeNode(int val, TreeNode left, TreeNode right) { |
| 12 | this.val = val; |
| 13 | this.left = left; |
| 14 | this.right = right; |
| 15 | } |
| 16 | } |
| 17 | |
| 18 | class Solution { |
| 19 | public List<List<Integer>> levelOrder(TreeNode root) { |