Count longest subsequence in string

Last updated: August 15, 2025

Quick Overview

Count the number of longest subsequence in the given interval list.

Lyft
Coding & Algorithms
Software Engineer
Lyft
August 15, 2025
Software Engineer
Take-home Project
Coding & Algorithms
Medium

307

3

4,909 solved


Count the number of longest subsequence in the given interval list.

This coding problem is frequently asked during Take-home Project at Lyft. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Lyft expects candidates to write production-quality code, not just solve the puzzle.

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
Sorting and searching
Time and space complexity analysis
Tree structures and recursion
Common algorithm patterns (sliding window, two pointers, BFS/DFS)
Edge cases and input validation
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
  • How would you modify your solution to handle streaming input?
  • How would you test this solution thoroughly?
  • Can you solve this in a single pass?
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