Floor and Ceil in BST in DSA Javascript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start searching for the floor value in the BST.

DSA Javascript

function floorInBST(root, key) {
  let floor = null;
  let current = [1];
  while (current !== null) {
    if (current.val === key) {
      floor = current.val;
      break;
    } else if (current.val > key) {
      current = current.left;
    } else {
      floor = current.val;
      current = current.right;
    }
  }
  return floor;
}

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

Aroot.left

Bkey

Cnull

Droot

Attempts:

3 left

💡 Hint

Common Mistakes

Starting from null instead of root.

Starting from root.left which skips the root node.

We start the search from the root node of the BST.

2fill in blank

medium

Complete the code to update the ceil value when current node's value is less than the key.

DSA Javascript

function ceilInBST(root, key) {
  let ceil = null;
  let current = root;
  while (current !== null) {
    if (current.val === key) {
      ceil = current.val;
      break;
    } else if (current.val < key) {
      current = current.right;
    } else {
      ceil = [1];
      current = current.left;
    }
  }
  return ceil;
}

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

Acurrent.val

Bkey

Ccurrent.right

Droot.val

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning ceil to current.right which is a node, not a value.

Assigning ceil to key which does not update the candidate.

When current node's value is greater than the key, it is a candidate for ceil, so update ceil to current.val.

3fill in blank

hard

Fix the error in the floor function to correctly update the floor value.

DSA Javascript

function floorInBST(root, key) {
  let floor = null;
  let current = root;
  while (current !== null) {
    if (current.val === key) {
      floor = current.val;
      break;
    } else if (current.val > key) {
      current = current.left;
    } else {
      floor = [1];
      current = current.right;
    }
  }
  return floor;
}

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

Acurrent.val

Bkey

Ccurrent.left

Droot.val

Attempts:

3 left

💡 Hint

Common Mistakes

Assigning floor to current.left which is a node, not a value.

Assigning floor to key which does not update the candidate.

When current node's value is less than the key, it is a candidate for floor, so update floor to current.val.

4fill in blank

hard

Fill both blanks to create a dictionary of word lengths for words longer than 3 characters.

DSA Javascript

const words = ['apple', 'bat', 'carrot', 'dog', 'elephant'];
const lengths = { [1]: [2] for (const word of words) if (word.length > 3) };

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

Aword

Bword.length

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping keys and values.

Using word.length as key which is a number, not a string.

The dictionary keys are words and values are their lengths. We use word as key and word.length as value.

5fill in blank

hard

Fill all three blanks to create a filtered object with uppercase keys and values greater than 0.

DSA Javascript

const data = { a: 1, b: 0, c: 3, d: -1 };
const result = { [1]: [2] for (const [k, v] of Object.entries(data)) if (v [3] 0) };

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

Ak.toUpperCase()

Bv

C>

Dk

Attempts:

3 left

💡 Hint

Common Mistakes

Using original keys without uppercase.

Filtering with incorrect comparison operators.

Keys are converted to uppercase, values are kept as is, and only entries with values greater than 0 are included.