├── README.md
└── zigzag-spiral-level-order-traversal.js


/README.md:
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 1 | # leetcode-javascript
 2 | 
 3 | This repo contains Javascript solution for famous Leetcode problems (with code + video explanation)
 4 | 
 5 | - **Binary Tree Zig-zag Level Order Traversal** : [Code](https://github.com/akshaymarch7/leetcode-javascript/blob/master/zigzag-spiral-level-order-traversal.js) , [Video Explanation](https://www.youtube.com/watch?v=4u--XDffIZM)
 6 | 
 7 | 
 8 | Hit that `Star` button to show some ❤️  
 9 | 
10 | Cheers,   
11 | Akshay Saini  
12 | [https://akshaysaini.in](https://akshaysaini.in)
13 | 


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/zigzag-spiral-level-order-traversal.js:
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 1 | /**
 2 | Given a binary tree, return the zigzag level order traversal of its nodes' values. 
 3 | (ie, from left to right, then right to left for the next level and alternate between).
 4 | 
 5 | For example:
 6 | Given binary tree [3,9,20,null,null,15,7],
 7 |     3
 8 |    / \
 9 |   9  20
10 |     /  \
11 |    15   7
12 |    
13 | return its zigzag level order traversal as:
14 | 
15 | [
16 |   [3],
17 |   [20,9],
18 |   [15,7]
19 | ]
20 | ====
21 | VIDEO EXPLANATION =  https://www.youtube.com/watch?v=4u--XDffIZM
22 | ====
23 | 
24 | **/
25 | 
26 | var zigzagLevelOrder = function(root) {
27 |     let results = [];
28 |     const lot = (root, level) => {
29 |         if(!root) return;
30 |         
31 |         if(results[level]) results[level].push(root.val);
32 |         else results[level] = [root.val];
33 |         
34 |         lot(root.left, level+1);
35 |         lot(root.right, level+1);
36 |     }
37 |     lot(root, 0);
38 |     return results.map((b,i)=>(i%2) ? b.reverse(): b);
39 | };
40 | 
41 | 


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