LintCode 70. Binary Tree Level Order Traversal II

题目

思路

代码

"""
Definition of TreeNode:
class TreeNode:
def __init__(self, val):
self.val = val
self.left, self.right = None, None
"""

class Solution:
"""
@param: root: A tree
@return: buttom-up level order a list of lists of integer
"""
def levelOrderBottom(self, root):
# write your code here
res_list = []
tmp_list = []
queue = []
lastNode = root
if root:
queue.append(root)
while queue:
root = queue[0]
queue.pop(0)
tmp_list.append(root.val)
if root.left:
queue.append(root.left)
if root.right:
queue.append(root.right)
if lastNode == root:
res_list.append(tmp_list)
tmp_list = []
if queue:
lastNode = queue[-1]
return res_list[::-1]