【python-leetcode103-树的宽度遍历】二叉树的锯齿形层次遍历

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

class Solution:
    def zigzagLevelOrder(self, root: TreeNode) -> List[List[int]]:
        from collections import deque
        if not root:
            return []
        queue=deque()
        queue.append(root)
        res=[]
        level=0
        while queue:
            tmp=deque()
            for i in range(len(queue)):
                t=queue.popleft()
                if level%2==0:
                    tmp.append(t.val)                
                else:
                    tmp.appendleft(t.val)
                if t.left:
                    queue.append(t.left)
                if t.right:
                    queue.append(t.right)
            level+=1
            res.append(list(tmp))
        return res