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103_binary_tree_zigzag_level_order_traversal.py
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103_binary_tree_zigzag_level_order_traversal.py
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#!/usr/bin/python
# -*- coding: utf-8 -*-
#author : zhangdawang
#data:2017-4-26
#difficulty degree:
#problem: 103_binary_tree_zigzag_level_order_traversal
#time_complecity:
#space_complecity:
#beats:
class TreeNode(object):
def __init__(self, x):
self.val = x
self.left = None
self.right = None
def CreateTree(self, tree, nums, i):
if i >= len(nums) // 2:
return
if nums[2 * i] != 0:
tree.left = TreeNode(nums[2 * i])
self.CreateTree(tree.left, nums, 2*i)
if nums[2 * i + 1] != 0:
tree.right = TreeNode(nums[2 * i + 1])
self.CreateTree(tree.right, nums, 2*i + 1)
def GenerateTree(self, nums):
root = TreeNode(nums[1])
self.CreateTree(root, nums, 1)
return root
class Solution(object):
def zigzagLevelOrder(self, root):
res = []
queue = [root]
reverse = 0
while queue:
temp = []
queue.append("#")
while True:
q = queue.pop(0)
if q =="#":
break
if q == None:
continue
temp.append(q.val)
queue.append(q.left)
queue.append(q.right)
if reverse:
temp.reverse()
res.append(temp)
reverse = (reverse + 1)%2
res.pop()
return res
def zigzagLevelOrder2(self, root):
if not root: return []
res, temp, stack, flag=[], [], [root], 1
while stack:
for i in range(len(stack)):
node=stack.pop(0)
temp+=[node.val]
if node.left: stack+=[node.left]
if node.right: stack+=[node.right]
res+=[temp[::flag]]
temp=[]
flag*=-1
return res
nums = [0,3,9,20,0,0,15,7]
a = TreeNode(1)
root = a.GenerateTree(nums)
solute = Solution()
res = solute.zigzagLevelOrder(root)
print(res)