Tree Traversal Level Order BFS in DSA C++ - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a queue for BFS traversal.

DSA C++

std::queue<[1]> q;

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ATreeNode*

Bint

Cstring

Dvector<int>

Attempts:

3 left

💡 Hint

Common Mistakes

Using int instead of TreeNode* in the queue declaration.

Using vector which is not suitable for BFS queue.

The queue should hold pointers to TreeNode objects for BFS traversal.

2fill in blank

medium

Complete the code to push the root node into the queue.

DSA C++

q.[1](root);

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Apop

Bpush

Cfront

Dempty

Attempts:

3 left

💡 Hint

Common Mistakes

Using pop() instead of push() to add elements.

Using front() which only accesses but does not add.

We use push() to add the root node to the queue.

3fill in blank

hard

Fix the error in the loop condition to continue BFS while the queue is not empty.

DSA C++

while (!q.[1]()) {

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Afront

Bsize

Cpop

Dempty

Attempts:

3 left

💡 Hint

Common Mistakes

Using front() or pop() in the condition which are not boolean checks.

Using size() without comparison.

We check if the queue is empty using empty() method.

4fill in blank

hard

Fill both blanks to get the front node and then remove it from the queue.

DSA C++

TreeNode* node = q.[1]();
q.[2]();

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Afront

Bpop

Cpush

Dempty

Attempts:

3 left

💡 Hint

Common Mistakes

Using push() instead of pop() to remove elements.

Using empty() which only checks if queue is empty.

front() gets the first element, pop() removes it from the queue.

5fill in blank

hard

Fill all three blanks to add the left child to the queue if it exists.

DSA C++

if (node->[1] != nullptr) q.[2](node->[3]);

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Aleft

Bpush

Cright

Dpop

Attempts:

3 left

💡 Hint

Common Mistakes

Using pop() instead of push() to add children.

Checking right child but pushing left child or vice versa.

Check if left child exists, then push it to the queue.