Optimize compression for without recursion
Last updated: November 10, 2025
Quick Overview
Given a string, implement a function to optimize its compression without using recursion. The function should return a compressed version of the string where consecutive duplicate characters are replaced by the character followed by the count of its occurrences. For example, the input "aaabbc" should return "a3b2c1".
Vercel
November 10, 20257
14
1,499 solved
Given a string, implement a function to optimize its compression without using recursion. The function should return a compressed version of the string where consecutive duplicate characters are replaced by the character followed by the count of its occurrences. For example, the input "aaabbc" should return "a3b2c1".
Vercel uses this problem in the Technical Screen 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
- Recognize the underlying problem pattern (sliding window, two pointers, BFS/DFS, etc.)
- Discuss multiple approaches and trade-offs before coding
- Implement an optimal solution with clean, production-quality code
- Handle all edge cases including boundary conditions and invalid input
- Optimize both time and space complexity with clear justification
- Test your solution systematically with well-chosen examples
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 happens if the input contains duplicates?
- Can you solve this in a single pass?
- How would you parallelize this solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires compressing a string by replacing consecutive duplicate characters with the character followed by the count of its occurrences. This is a classic application of the 'two pointers'...
Approach
- Initialize an empty result list to build the compressed string.
- Use a pointer
ito iterate through the string. Initialize a count variable to 1. - For each character at index
i, check if th...
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