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Akshay Saini
Akshay Saini

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ZigZag (Spiral) Level Order Traversal 🔥 | Amazon Interview Question

Binary Tree Zig-zag Level Order Traversal a.k.a. Spiral Level Order Traversal has been frequently asked in Coding Interviews of Amazon, Google, Microsoft, Facebook, Apple, LinkedIn, Samsung, Walmart, and a lot of other tech giants.

Do give it a try, but what if you're stuck somewhere?
No need to worry. This article contains a working solution to this Leetcode Medium problem using Javascript. ❤️

Towards the end of this post, I also have a Youtube video attached, you can also watch a step by step solution there if needed. All the best for your coding Interviews. 👍🏾

Problem Statement:

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).

Given binary tree [3,9,20,null,null,15,7],

  / \
 9   20
    /  \
  15    7

Return its zigzag level order traversal as:


Javascript Code:

Below is the Javascript code for this Leetcode Medium problem of Spiral Level Order traversal.

var zigzagLevelOrder = function(root) {
    let results = [];
    const lot = (root, level) => {
        if(!root) return;

        if(results[level]) results[level].push(root.val);
        else results[level] = [root.val];

        lot(root.left, level+1);
        lot(root.right, level+1);
    lot(root, 0);
    return,i)=>(i%2) ? b.reverse(): b);

Step by Step Explanation in below Youtube Video:

Below is the Youtube video explaining this frequently asked Interview question of Binary Tree Spiral Level Order Traversal.

If you like this initiative of solving DS/ Algo Coding Interview Problems from Leetcode using Javascript then do give it a thumbs up and comment down your feedback.

You can also check out this Github Repository for all the code and video links in this #DSinJS series on Youtube.

Akshay Saini

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