Tree Traversal Level Order BFS in DSA Javascript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize the queue with the root node.

DSA Javascript

const queue = [[1]];

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

A[]

Bnull

Cundefined

Droot

Attempts:

3 left

💡 Hint

Common Mistakes

Initializing the queue as empty or with null causes no nodes to be processed.

The queue should start with the root node to begin level order traversal.

2fill in blank

medium

Complete the code to remove the first node from the queue.

DSA Javascript

const current = queue.[1]();

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

Apop

Bshift

Cunshift

Dpush

Attempts:

3 left

💡 Hint

Common Mistakes

Using pop() removes the last node, breaking the BFS order.

In level order traversal, we remove nodes from the front of the queue using shift().

3fill in blank

hard

Fix the error in adding the left child to the queue only if it exists.

DSA Javascript

if (current.left) queue.[1](current.left);

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

Apop

Bshift

Cpush

Dunshift

Attempts:

3 left

💡 Hint

Common Mistakes

Using pop() or shift() to add nodes causes errors or wrong order.

We add children to the end of the queue using push() to maintain BFS order.

4fill in blank

hard

Fill both blanks to add the right child to the queue only if it exists.

DSA Javascript

if (current.[1]) queue.[2](current.right);

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

Aright

Bleft

Cpush

Dshift

Attempts:

3 left

💡 Hint

Common Mistakes

Checking left instead of right child.

Using shift() instead of push() to add nodes.

Check if current.right exists, then add it to the queue with push().

5fill in blank

hard

Fill all three blanks to complete the while loop condition and add children to the queue.

DSA Javascript

while (queue.[1] > 0) {
  const current = queue.[2]();
  if (current.left) queue.[3](current.left);
}

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

Alength

Bshift

Cpush

Dpop

Attempts:

3 left

💡 Hint

Common Mistakes

Using pop() to remove nodes breaks BFS order.

Checking queue with wrong property or method.

The loop runs while the queue has nodes (length > 0), removes the first node (shift()), and adds left child (push()).