BST vs Hash Map Trade-offs for Ordered Data in DSA Javascript - Interactive Comparison Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to insert a value into a Binary Search Tree (BST).

DSA Javascript

function insertNode(root, value) {
  if (root === null) {
    return { val: value, left: null, right: null };
  }
  if (value [1] root.val) {
    root.left = insertNode(root.left, value);
  } else {
    root.right = insertNode(root.right, value);
  }
  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 '<' causes wrong placement in the tree.

Using '===' will never insert new nodes properly.

In a BST, values less than the current node go to the left subtree. So we check if value < root.val.

2fill in blank

medium

Complete the code to check if a key exists in a JavaScript Map (hash map).

DSA Javascript

function hasKey(map, key) {
  return map.[1](key);
}

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

Ahas

Bfind

Ccontains

Dincludes

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'includes' which works on arrays, not Maps.

Using 'find' which is not a Map method.

The Map object in JavaScript uses the has method to check for keys.

3fill in blank

hard

Fix the error in the code to find the minimum value node in a BST.

DSA Javascript

function findMinNode(node) {
  while (node.[1] !== null) {
    node = node.left;
  }
  return node;
}

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

Aright

Bval

Cparent

Dleft

Attempts:

3 left

💡 Hint

Common Mistakes

Checking 'right' instead of 'left' leads to wrong minimum.

Checking 'val' or 'parent' properties causes errors.

The minimum value in a BST is found by going as far left as possible, so we check node.left.

4fill in blank

hard

Fill both blanks to create a Map from an array of keys with initial value 0, but only for keys longer than 3 characters.

DSA Javascript

const keys = ['apple', 'bat', 'carrot', 'dog'];
const map = new Map();
for (const key of keys) {
  if (key.[1] > 3) {
    map.[2](key, 0);
  }
}

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

Alength

Bset

Cpush

Dsize

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'size' instead of 'length' for strings.

Using 'push' which is for arrays, not Maps.

We check the length of the string with key.length and add to Map using map.set(key, 0).

5fill in blank

hard

Fill all three blanks to create an object that maps keys to their lengths, but only include keys with length less than 5.

DSA Javascript

const keys = ['sun', 'moon', 'star', 'sky'];
const result = {
  [1]: [2] for [3] of keys if [2] < 5
};

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

Akey

Blen

Cfor key

Dkey.length

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'len' which is Python style, not JavaScript.

Confusing the loop syntax.

This is a JavaScript object comprehension style (conceptual) where key is the property, key.length is the value, and we loop with for key.