The Level Inspector

A medium Python interview practice problem on DataDriven. Write and execute real python code with instant grading.

Domain

Python

Difficulty

medium

Seniority

L4

Problem

You're handed a binary tree decoded from a nested-dict export: each node is a dict with an int `val` plus `left` and `right` children that are either another such node or `None`. Group the values by depth, returning a list whose entry at index i holds every value at depth i in left-to-right order, with the root sitting at depth 0. An empty tree, where `root` is `None`, comes back as an empty list.

Summary

Each floor of the tower tells a different story.

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