Zigzag Level Order Traversal in DSA Typescript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the queue with the root node for level order traversal.

DSA Typescript

const queue: TreeNode[] = [[1]];

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Aundefined

Bnull

C[]

Droot

Attempts:

3 left

💡 Hint

Common Mistakes

Initializing queue with null or empty array instead of root node.

We start the traversal by adding the root node to the queue.

2fill in blank

medium

Complete the code to toggle the direction of traversal after each level.

DSA Typescript

leftToRight = ![1];

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Aqueue

BleftToRight

ClevelNodes

Dresult

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to toggle the wrong variable or using assignment instead of negation.

We flip the boolean leftToRight to change the traversal direction for the next level.

3fill in blank

hard

Fix the error in the code that reverses the level nodes when traversing right to left.

DSA Typescript

if (!leftToRight) levelNodes.[1]();

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Apop

Bsort

Creverse

Dshift

Attempts:

3 left

💡 Hint

Common Mistakes

Using sort() which sorts alphabetically or numerically, not reversing.

Using pop() or shift() which remove elements instead of reversing.

We use reverse() to flip the order of nodes for right-to-left traversal.

4fill in blank

hard

Fill both blanks to correctly add child nodes to the queue for the next level.

DSA Typescript

if (node.[1]) queue.push(node.[2]);

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Aleft

Bright

Cparent

Dchild

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing left and right properties incorrectly.

Using non-existent properties like parent or child.

We check if the left child exists and then add it to the queue.

5fill in blank

hard

Fill all three blanks to correctly add the right child node to the queue if it exists.

DSA Typescript

if (node.[1]) queue.[2](node.[3]);

Drag options to blanks, or click blank then click option'

Aleft

Bpush

Cright

Dpop

Attempts:

3 left

💡 Hint

Common Mistakes

Using left instead of right for the child node.

Using pop instead of push to add nodes.

We check if the right child exists and then push it to the queue.