Optimize compression for with follow-up
Last updated: October 24, 2025
Quick Overview
Given a string, implement a function to optimize its compression by replacing consecutive repeating characters with the character followed by the count of repetitions. The function should return the compressed string, and if the compressed string is not shorter than the original, return the original string instead. For example, the input "aabcccccaaa" should return "a2b1c5a3".
Compass
October 24, 202511
6
2,918 solved
Given a string, implement a function to optimize its compression by replacing consecutive repeating characters with the character followed by the count of repetitions. The function should return the compressed string, and if the compressed string is not shorter than the original, return the original string instead. For example, the input "aabcccccaaa" should return "a2b1c5a3".
Compass uses this problem in the Onsite to evaluate your algorithmic thinking. They expect you to discuss multiple approaches, analyze trade-offs between them, and implement the optimal solution with clean, readable code.
What the Interviewer Expects
- Identify the correct data structure and algorithm for the problem
- Write clean, bug-free code with proper variable naming
- Analyze time and space complexity correctly
- Handle basic edge cases (empty input, single element)
- Communicate your thought process while coding
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
- What is the worst-case input for your solution?
- How would you test this solution thoroughly?
- Can you optimize the space complexity of your solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires us to compress a string by replacing consecutive repeating characters with the character followed by the count of repetitions. The two-pointer technique is particularly useful her...
Approach
- Initialize an empty list to hold the compressed parts of the string and a pointer to iterate through the string.
- Use a while loop to traverse the string. For each character, count how many times...
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