Lowest Common Ancestor in Binary Tree in DSA Typescript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if the current node is null.

DSA Typescript

if (root [1] null) return null;

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

A===

B!==

C>=

D<=

Attempts:

3 left

💡 Hint

Common Mistakes

Using != instead of ===

Using assignment operator = instead of comparison

Checking for undefined instead of null

We check if root is exactly equal to null to stop recursion.

2fill in blank

medium

Complete the code to check if the current node is either p or q.

DSA Typescript

if (root [1] p || root [1] q) return root;

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

A>

B===

C!==

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using != instead of ===

Using > or < which are not suitable for equality checks

We compare root with p and q using strict equality.

3fill in blank

hard

Fix the error in the recursive calls to search left and right subtrees.

DSA Typescript

const left = lowestCommonAncestor(root.[1], p, q);
const right = lowestCommonAncestor(root.[2], p, q);

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

Aleft

Bright

CleftChild

DrightChild

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect property names like leftChild or rightChild

Swapping left and right

The left subtree is accessed by root.left and the right subtree by root.right.

4fill in blank

hard

Fill both blanks to return the correct node based on left and right subtree results.

DSA Typescript

if (left [1] null && right [2] null) return root;

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

A!==

B===

C&&

D||

Attempts:

3 left

💡 Hint

Common Mistakes

Using === instead of !==

Using logical OR instead of AND

If both left and right are not null, the current root is the lowest common ancestor.

5fill in blank

hard

Fill the blank to return the non-null subtree or null if both are null.

DSA Typescript

return left [1] right;

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

A&&

B===

C!==

D||

Attempts:

3 left

💡 Hint

Common Mistakes

Using && which requires both to be true

Using equality operators which are not suitable here

We use logical OR || to return the non-null subtree or null if both are null.