How should I practice Binary Tree Level Order Traversal?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Google onsite interview problems in FastPrep.

Is Binary Tree Level Order Traversal associated with Google?

FastPrep tags this as a Google onsite interview coding practice problem when the problem catalog has that company and stage context.

Binary Tree Level Order Traversal

Google● MediumFULLTIMEINTERNONSITE INTERVIEW

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Problem statement

Given the root of a binary tree, return its node values grouped by depth from top to bottom. Values within each level must appear from left to right. Return an empty list for an empty tree.

Function

levelOrder(root: TreeNode) → List<List<Integer>>

Examples

Example 1

root = [3,9,20,null,null,15,7]return = [[3],[9,20],[15,7]]

The root forms level zero, its two children form level one, and nodes 15 and 7 form level two.

Example 2

root = [1,null,2,3]return = [[1],[2],[3]]

Each node occupies a separate depth even though the tree is skewed.

Example 3

root = []return = []

An empty tree has no levels.

Constraints

The tree contains at most 100000 nodes.
Each node value is between -10^9 and 10^9.