103. Binary Tree Zigzag Level Order Traversal
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] ]
题意：二叉搜索树的层序遍历的变形，z形遍历
代码如下：
/** * Definition for a binary tree node. * function TreeNode(val) { * this.val = val; * this.left = this.right = null; * } */ /** * @param {TreeNode} root * @return {number[][]} */ var zigzagLevelOrder = function(root) { let res=[]; helper(root,res,0); return res; }; var helper=function(root,res,level){ if(!root) return ; if(!res[level]) res[level]=[]; level%2 ? res[level].unshift(root.val) :res[level].push(root.val); helper(root.left,res,level+1); helper(root.right,res,level+1); }
103. Binary Tree Zigzag Level Order Traversal（js）
原文：https://www.cnblogs.com/xingguozhiming/p/10713062.html