Binary Tree Zigzag Level Order Traversal.md

Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right to left for the next level and alternate between).

For example:
Given binary tree [3,9,20,null,null,15,7],
    3
   / \
  9  20
    /  \
   15   7
return its zigzag level order traversal as:
[
  [3],
  [20,9],
  [15,7]
]

My code:

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
    def zigzagLevelOrder(self, root):
        """
        :type root: TreeNode
        :rtype: List[List[int]]
        """
        if root==None:
            return []
        search_list=[root]
        read_label=True
        record_list=[]
        while search_list:
            tmp_record=[]
            will_search=[]
            for item in search_list:
                left=item.left
                if left!=None:
                    will_search.append(left)
                right=item.right
                if right!=None:
                    will_search.append(right)
                tmp_record.append(item.val)
            if not read_label:
                tmp_record.reverse()
            search_list=will_search
            record_list.append(tmp_record)
            read_label=not read_label
        return record_list
                

Solution: https://leetcode.com/problems/binary-tree-zigzag-level-order-traversal/submissions/