Detect subsequence in string
Last updated: November 20, 2025
Quick Overview
Given a string and a subsequence, determine if the subsequence can be found within the string while maintaining the order of characters. The function should return a boolean value indicating whether the subsequence exists in the string. For example, given the string "abcde" and the subsequence "ace", the output should be true, while for "aec", it should be false.
Zillow
November 20, 202574
11
1,188 solved
Given a string and a subsequence, determine if the subsequence can be found within the string while maintaining the order of characters. The function should return a boolean value indicating whether the subsequence exists in the string. For example, given the string "abcde" and the subsequence "ace", the output should be true, while for "aec", it should be false.
Coding interviews at Zillow focus on problem-solving approach as much as the final solution. The interviewer wants to see you break down the problem, consider edge cases, and optimize iteratively. Communication throughout the process is key.
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
- How would you parallelize this solution?
- How would you test this solution thoroughly?
- Can you solve this iteratively instead of recursively (or vice versa)?
- What happens if the input contains duplicates?
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Practice DSA ProblemsSample Answer
Problem Analysis
To determine if a subsequence exists within a string while maintaining the order of characters, we can recognize this as a typical two-pointer problem. The two-pointer technique is appropriate here be...
Approach
We can implement the solution using a two-pointer technique. The steps are as follows:
- Initialize two pointers:
ifor the main string andjfor the subsequence, both starting at 0. - Iterate t...
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