Tree Traversal Level Order BFS in DSA Javascript - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Level Order Traversal in a tree?

Level Order Traversal visits nodes level by level from top to bottom and left to right within each level.

beginner

Which data structure is commonly used to implement Level Order Traversal (BFS) in trees?

A queue is used to keep track of nodes to visit next in Level Order Traversal.

beginner

What is the time complexity of Level Order Traversal on a binary tree with n nodes?

The time complexity is O(n) because each node is visited exactly once.

intermediate

In Level Order Traversal, what happens when a node is dequeued?

When a node is dequeued, its value is processed (e.g., printed), and its children are enqueued for later visits.

intermediate

Why is Level Order Traversal also called Breadth-First Search (BFS)?

Because it explores all nodes at the current depth before moving to nodes at the next depth, spreading out like a wave.

What data structure is essential for implementing Level Order Traversal?

A Queue

B Stack

C Hash Map

D Linked List

A queue is used to process nodes in the order they are discovered, which is key for Level Order Traversal.

In Level Order Traversal, which node is visited first?

A Rightmost leaf node

B Leftmost leaf node

C Root node

D Any random node

Traversal starts at the root node and proceeds level by level.

What is the order of visiting nodes in Level Order Traversal?

A Left subtree, root, right subtree

B Top to bottom, left to right

C Bottom to top, right to left

D Right subtree, root, left subtree

Nodes are visited level by level from top to bottom and within each level from left to right.

What happens to the children of a node during Level Order Traversal?

A They are added to the queue

B They are ignored

C They are processed immediately

D They are deleted

Children are enqueued to be visited after all nodes at the current level.

What is the time complexity of Level Order Traversal on a tree with n nodes?

A O(1)

B O(log n)

C O(n^2)

D O(n)

Each node is visited once, so the time complexity is linear in the number of nodes.

Explain how Level Order Traversal (BFS) works on a binary tree step-by-step.

Think about visiting nodes like visiting friends floor by floor in a building.

Describe the difference between Level Order Traversal and Depth First Traversal in trees.

Compare exploring a tree floor by floor versus going deep down one branch first.