Detect subsequence in matrix
Last updated: April 27, 2026
Quick Overview
Given a 2D matrix of characters and a sequence of characters, determine if the sequence can be found as a subsequence in the matrix by traversing from left to right or top to bottom. The function should return true if the subsequence exists and false otherwise.
Supabase
April 27, 202646
9
4,915 solved
Given a 2D matrix of characters and a sequence of characters, determine if the sequence can be found as a subsequence in the matrix by traversing from left to right or top to bottom. The function should return true if the subsequence exists and false otherwise.
Coding interviews at Supabase 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
- 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
- Can you solve this in a single pass?
- How would you parallelize this solution?
- Can you solve this iteratively instead of recursively (or vice versa)?
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Problem Analysis
To determine if a given sequence of characters can be found as a subsequence in a 2D matrix, we need to traverse the matrix from left to right or top to bottom. This scenario suggests the use of a dep...
Approach
- Start at the top-left corner of the matrix (0, 0).
2. For each character in the sequence, check if it matches the current character in the matrix.
3. If it matches, recursively attempt to...
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