LC103 Binary Tree Zigzag Level Order Traversal

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def zigzagLevelOrder(self, root: TreeNode) -> List[List[int]]:
        level = 0 
        res = []
        if not root:
            return res
        q = collections.deque()
        q.append(root)
        while q:
            size = len(q)
            temp = []
            for i in range(size):
                node = q.popleft()
                temp.append(node.val)
                if node.left:
                    q.append(node.left)
                if node.right:
                    q.append(node.right)
            if level % 2 !=0:
                res.append(temp[::-1])
            else:
                res.append(temp)
            level += 1
        return res