Diameter of Binary Tree in DSA Javascript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to calculate the height of a binary tree node.

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'

Aparent

Broot

Cright

Dchild

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'parent' instead of 'right' causes undefined errors.

Using 'child' or 'root' are not valid properties of a node.

The height function calculates the height of a node by recursively checking the left and right children. The correct property to access the right child is 'right'.

2fill in blank

medium

Complete the code to update the diameter during traversal.

DSA Javascript

function diameterOfBinaryTree(root) {
  let diameter = 0;
  function dfs(node) {
    if (node === null) return 0;
    let leftHeight = dfs(node.left);
    let rightHeight = dfs(node.right);
    diameter = Math.max(diameter, leftHeight + rightHeight);
    return 1 + Math.max(leftHeight, [1]);
  }
  dfs(root);
  return diameter;
}

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

Anode

Bdiameter

Croot

DrightHeight

Attempts:

3 left

💡 Hint

Common Mistakes

Returning diameter instead of rightHeight causes wrong height calculation.

Returning node or root is incorrect as they are objects, not heights.

The function returns the height of the current node, which is 1 plus the maximum height of its left and right children. So, it should return 1 + Math.max(leftHeight, rightHeight).

3fill in blank

hard

Fix the error in the recursive function call to avoid infinite recursion.

DSA Javascript

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

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

Aright

Bleft

Cparent

Dnode

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'left' twice causes missing right subtree traversal.

Using 'parent' causes infinite recursion or errors.

The recursive call should be on the right child of the node, which is accessed by 'right'. Using 'parent' or 'node' would cause errors or infinite recursion.

4fill in blank

hard

Fill both blanks to correctly update the diameter and return the height.

DSA Javascript

function dfs(node) {
  if (node === null) return 0;
  let leftHeight = dfs(node.left);
  let rightHeight = dfs(node.right);
  diameter = Math.max(diameter, leftHeight [1] rightHeight);
  return 1 [2] Math.max(leftHeight, rightHeight);
}

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

A+

B-

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-' or '*' causes wrong diameter or height calculations.

Using '/' causes runtime errors or wrong results.

The diameter is updated by adding leftHeight and rightHeight. The height is 1 plus the maximum of leftHeight and rightHeight, so both blanks use '+'.

5fill in blank

hard

Fill all three blanks to complete the diameter calculation using a helper function.

DSA Javascript

function diameterOfBinaryTree(root) {
  let diameter = 0;
  function dfs(node) {
    if (node === null) return 0;
    let leftHeight = dfs(node.left);
    let rightHeight = dfs(node.right);
    diameter = Math.max(diameter, leftHeight [1] rightHeight);
    return 1 + Math.max(leftHeight, [2]);
  }
  dfs([3]);
  return diameter;
}

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

A+

BrightHeight

Croot

DleftHeight

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong operators like '-' or '*' for diameter update.

Returning wrong variable instead of rightHeight.

Calling dfs on leftHeight or rightHeight instead of root.

The diameter is updated by adding leftHeight and rightHeight (use '+'). The height returned is 1 plus the max of leftHeight and rightHeight. The dfs function is called on the root node.