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103. Binary Tree Zigzag Level Order Traversal.go
103. Binary Tree Zigzag Level Order Traversal_test.go
README.md

README.md

103. Binary Tree Zigzag Level Order Traversal

题目

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]
]

题目大意

按照 Z 字型层序遍历一棵树。

解题思路

  • 按层序从上到下遍历一颗树,但是每一层的顺序是相互反转的,即上一层是从左往右,下一层就是从右往左,以此类推。用一个队列即可实现。
  • 第 102 题和第 107 题都是按层序遍历的。
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