Maximum Depth of Binary Tree

Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

一样的。

 1 /**

 2  * Definition for binary tree

 3  * public class TreeNode {

 4  *     int val;

 5  *     TreeNode left;

 6  *     TreeNode right;

 7  *     TreeNode(int x) { val = x; }

 8  * }

 9  */

10 public class Solution {

11     public int maxDepth(TreeNode root) {

12         // IMPORTANT: Please reset any member data you declared, as

13         // the same Solution instance will be reused for each test case.

14         ArrayList<TreeNode> queue = new ArrayList<TreeNode>();

15         int result = 0;

16         if(root == null) return result;

17         queue.add(root);

18         TreeNode nl = new TreeNode(Integer.MIN_VALUE);

19         queue.add(nl);

20         while(queue.size() != 1){

21             TreeNode rn = queue.remove(0);

22             if(rn.val == Integer.MIN_VALUE){

23                 queue.add(nl);

24                 result ++;

25             }

26             else{

27                 if(rn.left != null) queue.add(rn.left);

28                 if(rn.right != null) queue.add(rn.right);

29             }

30         }

31         return ++result;

32     }

33 }