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

Practice - 5 Tasks

1fill in blank

easy

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

DSA Typescript

function insertBST(root: TreeNode | null, val: number): TreeNode {
  if (root === null) {
    return new TreeNode(val);
  }
  if (val [1] root.val) {
    root.left = insertBST(root.left, val);
  } else {
    root.right = insertBST(root.right, val);
  }
  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 BST.

Using '===' will never insert properly.

In a BST, values less than the current node go to the left subtree.

2fill in blank

medium

Complete the code to check if a key exists in a Hash Map.

DSA Typescript

function hasKey(map: Map<string, number>, key: string): boolean {
  return map.[1](key);
}

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

Aget

Bcontains

Cfind

Dhas

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'get' returns the value or undefined, not a boolean.

Using 'find' or 'contains' are not valid Map methods.

The has method checks if a key exists in a Map.

3fill in blank

hard

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

DSA Typescript

function findMin(root: TreeNode | null): number | null {
  if (root === null) return null;
  let current = root;
  while (current.[1] !== null) {
    current = current.left;
  }
  return current.val;
}

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

Aleft

Bright

Cparent

Dchild

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'right' will find the maximum, not minimum.

Using 'parent' or 'child' are invalid properties.

The minimum value in a BST is found by going left until no more left child exists.

4fill in blank

hard

Fill both blanks to create a function that returns keys in sorted order from a BST.

DSA Typescript

function inorderTraversal(root: TreeNode | null, result: number[] = []): number[] {
  if (root !== null) {
    inorderTraversal(root.[1], result);
    result.push(root.val);
    inorderTraversal(root.[2], result);
  }
  return result;
}

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

Aleft

Bright

Cparent

Dchild

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping left and right changes the order.

Using 'parent' or 'child' causes errors.

Inorder traversal visits left subtree, then node, then right subtree, producing sorted keys.

5fill in blank

hard

Fill all three blanks to create a function that counts keys in a Hash Map greater than a threshold.

DSA Typescript

function countGreaterThan(map: Map<string, number>, threshold: number): number {
  let count = 0;
  for (const [1] of map.entries()) {
    const [key, value] = [2];
    if (value [3] threshold) {
      count++;
    }
  }
  return count;
}

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

Aentry

B>

C<

Ditem

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' counts values less than threshold.

Using wrong variable names causes errors.

We iterate over entries, unpack each entry, and count values greater than threshold.