Optimize inversion for in-place

Last updated: February 12, 2026

Quick Overview

Find an efficient solution for compression given the in-place constraint.

Compass
Coding & Algorithms
Software Engineer
Compass
February 12, 2026
Software Engineer
Take-home Project
Coding & Algorithms
Hard

35

12

961 solved


Find an efficient solution for compression given the in-place constraint.

This coding problem is frequently asked during Take-home Project at Compass. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Compass 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
Sorting and searching
Data structure selection and trade-offs
Dynamic programming and memoization
Binary search and divide and conquer
How to Approach This
  1. Clarify input constraints and edge cases before writing code.
  2. Walk through your approach verbally and confirm with the interviewer before coding.
  3. Start with a brute force solution, then optimize. Mention time and space complexity.
  4. Test your solution with examples, including edge cases like empty input or duplicates.
  5. Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
  • Can you solve this in a single pass?
  • What is the worst-case input for your solution?
  • How would you modify your solution to handle streaming input?
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