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题目：
Given a binary tree, return the bottom-up level order traversal of its nodes‘ values. (ie, from left to right, level by level from leaf to root).
For example:
Given binary tree {3,9,20,#,#,15,7},
3
/ 9 20
/ 15 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.
链接： http://leetcode.com/problems/binary-tree-level-order-traversal-ii/
一刷，比102题只多了最后一步，还是用了2个list，第二遍可以试一下DFS
1 class Solution(object): 2 def levelOrderBottom(self, root): 3 if not root: 4 return [] 5 result = [] 6 prev = [root] 7 cur = [] 8 9 while prev: 10 for elem in prev: 11 if elem.left: 12 cur.append(elem.left) 13 if elem.right: 14 cur.append(elem.right) 15 result.append([e.val for e in prev]) 16 prev, cur = cur, [] 17 result.reverse() 18 return result
107. Binary Tree Level Order Traversal II
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原文地址：http://www.cnblogs.com/panini/p/5597287.html
