Height of Binary Tree in DSA Javascript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to return the height of a binary tree recursively.

DSA Javascript

function height(node) {
  if (node === null) {
    return 0;
  }
  return 1 + Math.max(height(node.left), height(node[1]));
}

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

A.parent

B.right

C.left

D.child

Attempts:

3 left

💡 Hint

Common Mistakes

Using node.left twice instead of node.right

Using node.parent which is not part of height calculation

The height of a binary tree is 1 plus the maximum height of its left and right subtrees. We already have height(node.left), so the other subtree is node.right.

2fill in blank

medium

Complete the code to check if the node is null before calculating height.

DSA Javascript

function height(node) {
  if (node [1] null) {
    return 0;
  }
  return 1 + Math.max(height(node.left), height(node.right));
}

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

A===

B!==

C==

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using !== which reverses the logic

Using loose equality == which can cause unexpected results

We check if node is exactly null to stop recursion and return 0 height for empty subtree.

3fill in blank

hard

Fix the error in the recursive call to height for the right subtree.

DSA Javascript

function height(node) {
  if (node === null) {
    return 0;
  }
  return 1 + Math.max(height(node.left), height(node[1]));
}

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

A.rigt

B.parent

C.right

D.leftt

Attempts:

3 left

💡 Hint

Common Mistakes

Typos like '.leftt' or '.rigt'

Using '.parent' which is not a child node

The correct property for the right child is node.right. Misspelled properties cause runtime errors.

4fill in blank

hard

Fill both blanks to create a function that returns the height of a binary tree using recursion.

DSA Javascript

function height(node) {
  if (node [1] null) {
    return 0;
  }
  return 1 + Math.max(height(node[2]), height(node.right));
}

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

A===

B!==

C.left

D.parent

Attempts:

3 left

💡 Hint

Common Mistakes

Using !== instead of === in null check

Using '.parent' instead of '.left' for child node

Check if node is exactly null, then recursively get height of left and right children.

5fill in blank

hard

Fill all three blanks to complete the height function with correct null check and recursive calls.

DSA Javascript

function height(node) {
  if (node [1] null) {
    return 0;
  }
  return 1 + Math.max(height(node[2]), height(node[3]));
}

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

A!==

B===

C.right

D.left

Attempts:

3 left

💡 Hint

Common Mistakes

Using !== instead of === for null check

Swapping left and right child properties

Use strict equality to check null, then recursively call height on left and right children.