Detect subsequence in matrix
Last updated: September 11, 2025
Quick Overview
Given a 2D matrix of characters and a string, determine if the string can be found as a subsequence in the matrix by traversing adjacent cells (horizontally or vertically). Return true if the subsequence exists, otherwise return false. The input consists of the matrix dimensions and the target string, while the output is a boolean value indicating the presence of the subsequence.
Netflix
September 11, 2025197
12
1,063 solved
Given a 2D matrix of characters and a string, determine if the string can be found as a subsequence in the matrix by traversing adjacent cells (horizontally or vertically). Return true if the subsequence exists, otherwise return false. The input consists of the matrix dimensions and the target string, while the output is a boolean value indicating the presence of the subsequence.
Netflix uses this problem in the Phone 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
- 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
- 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?
- What if the input doesn't fit in memory?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires us to determine if a given string can be found as a subsequence in a 2D matrix of characters by traversing adjacent cells (horizontally or vertically). This is a classic problem t...
Approach
- Iterate through each cell in the matrix. For each cell that matches the first character of the string, initiate a DFS search.
- In the DFS function, check if the current position matches the cor...
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