Optimize flattening for with follow-up
Last updated: March 12, 2026
Quick Overview
Given a nested list of integers, implement a function to flatten the list while optimizing for memory usage, and handle a follow-up requirement where you must also return the depth of the original nested structure. The function should take a list as input and return a tuple containing the flattened list and the maximum depth as output.
Apple
March 12, 202649
3
1,869 solved
Given a nested list of integers, implement a function to flatten the list while optimizing for memory usage, and handle a follow-up requirement where you must also return the depth of the original nested structure. The function should take a list as input and return a tuple containing the flattened list and the maximum depth as output.
This coding problem is frequently asked during Take-home Project at Apple. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Apple expects candidates to write production-quality code, not just solve the puzzle.
What the Interviewer Expects
- Quickly identify the optimal approach and its theoretical basis
- Handle complex algorithm design with multiple interacting components
- Write concise, elegant code under time pressure
- Prove correctness of your approach and discuss alternative solutions
- Optimize beyond the obvious: discuss constant factor improvements
- Address follow-up variations and explain how the solution generalizes
Key Topics to Cover
How to Approach This
- Clarify input constraints and edge cases before writing code.
- Walk through your approach verbally and confirm with the interviewer before coding.
- Start with a brute force solution, then optimize. Mention time and space complexity.
- Test your solution with examples, including edge cases like empty input or duplicates.
- Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
- How would you test this solution thoroughly?
- How would you modify your solution to handle streaming input?
- How would your solution change if the input was sorted?
- How would you parallelize this solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires flattening a nested list of integers while also tracking the maximum depth of the nested structure. This can be efficiently solved using a recursive Depth-First Search (DFS) appro...
Approach
The algorithm follows these steps:
- Initialize an empty list to hold the flattened integers and a variable to track the maximum depth.
- Define a recursive function that takes two parameters: the c...
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