Tree Traversal Level Order BFS in DSA Go - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

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

DSA Go

queue := []*TreeNode[1]

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ATreeNode{}

Bnil

Croot

D[]

Attempts:

3 left

💡 Hint

Common Mistakes

Initializing queue as empty instead of with root node

Using nil instead of root

Using an empty struct instead of the root pointer

We start the BFS by adding the root node to the queue.

2fill in blank

medium

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

DSA Go

node := queue[[1]]
queue = queue[1:]

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A0

B1

C-1

Dlen(queue)

Attempts:

3 left

💡 Hint

Common Mistakes

Using index 1 which skips the first element

Using negative index which is invalid

Using length of queue which is out of range

In Go slices, the first element is at index 0, so we dequeue from index 0.

3fill in blank

hard

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

DSA Go

if node.Left [1] nil {
    queue = append(queue, node.Left)
}

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A>

B==

C<

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Checking if left child is equal to nil instead of not equal

Using comparison operators like < or > which are invalid for pointers

We add the left child only if it is not nil (exists).

4fill in blank

hard

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

DSA Go

if node.Right [1] nil {
    queue = append(queue, node.Right)
}
[2]

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A!=

B==

Ccontinue

Dbreak

Attempts:

3 left

💡 Hint

Common Mistakes

Using '==' instead of '!=' to check for nil

Using 'break' instead of 'continue' which stops the loop

We add the right child if it is not nil, then continue to the next iteration.

5fill in blank

hard

Fill all three blanks to complete the BFS loop that processes nodes until the queue is empty.

DSA Go

for len(queue) [1] 0 {
    node := queue[[2]]
    queue = queue[[3]:]
    // process node
}

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

A>

B0

C1

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' in loop condition

Using wrong indices for dequeue and slicing

The loop runs while queue length is greater than 0, dequeues from index 0, and slices from index 1 onward.