Leetcode Binary Tree level Order traversal II

Given a binary tree, return the bottom-up level order traversal of its nodes ' values. (ie, from the left-to-right, the level by level from the leaf to root).

For example:
Given binary Tree {3,9,20,#,#,15,7} ,

    3   /   9    /   7

Return its bottom-up level order traversal as:

[  [15,7],  [9,20],  [3]]

Confused what "{1,#,2,3}" means? > read more on how binary tree is serialized on OJ.

OJ ' s Binary Tree serialization:

The serialization of a binary tree follows a level order traversal, where ' # ' signifies a path terminator where no node ex Ists below.

Here's an example:

   1  /  2   3    /   4         5

The above binary tree is serialized as "{1,2,3,#,#,4,#,#,5}". Test instructions: traverse a tree backwards.

Idea: Still the same, the last inverted on the line

/** * Definition for a binary tree node.  * public class TreeNode {* int val, * TreeNode left, * TreeNode right; * TreeNode (int x) {val = x;} *} */public class Solution {public list<list<integer>> levelorderbottom (TreeNode root) {list<list        <Integer>> ans = new arraylist<list<integer>> ();                if (root = null) return ans;        queue<treenode> q = new linkedlist<treenode> ();        Q.add (root);        int count = 1, level = 0;        while (!q.isempty ()) {list<integer> tmp = new arraylist<integer> ();        level = 0;        for (int i = 0; i < count; i++) {TreeNode t = q.poll ();        Tmp.add (T.val);        if (t.left! = null) {Q.add (t.left);        ++level;        } if (t.right! = null) {Q.add (t.right);        ++level;        }} count = level;        Ans.add (TMP);      } collections.reverse (ANS);  return ans; }}

Leetcode Binary Tree level Order traversal II