leetcode 103 二叉树的锯齿形层序遍历

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

解题思路 : 

二叉树层序便利后, 偶数层子节点倒序即可.(第一层为root节点)

class Solution(object):

    def zigzagLevelOrder(self, root):

        self.n = 1

        self.queue = []

        self.result = []

        if root != None and root.left == None and root.right == None:

            tmp = [root.val]

            self.result.append(tmp)

            return self.result

        self.queue.append(root)

        while( len(self.queue) > 0 ):

            tmp = []

            tmp_list = []

            tmp_len = len(self.queue)

            for i in range(0, tmp_len):

                tmp_node = self.queue[0]

                if tmp_node != None:

                    tmp.append(tmp_node.val)

                    tmp_list.append(tmp_node.left)

                    tmp_list.append(tmp_node.right)

                del self.queue[0]

            self.queue = tmp_list

            self.n += 1

            if len(tmp) == 0:

                continue

            self.result.append(tmp)

        for i in range(0, len(self.result)):

            if i % 2 == 1:

                self.result[i] = list(reversed(self.result[i]))

        return self.result