[算法导论] 103. 二叉树的锯齿形层序遍历

 0.题目

 1. 双端队列

class Solution:
    def zigzagLevelOrder(self, root: TreeNode) -> List[List[int]]:
        if not root:
            return []
        c=1
        res = []
        parent = deque()
        parent.append(root)
        while parent: # 结点入数组
            tmp = []
            l = len(parent)
            for i in range(l):
                # print(parent)
                if c==1: #顺序
                    p = parent.popleft()
                    tmp.append(p.val)
                    if p.left:  parent.append(p.left) #加在后面
                    if p.right: parent.append(p.right)