Detect subsequence in matrix
Last updated: November 26, 2025
Quick Overview
Given a 2D matrix of characters and a string, determine if the string can be formed as a subsequence by traversing the matrix in a top-to-bottom and left-to-right manner. The function should return true if the string can be constructed as a subsequence from the matrix, and false otherwise. The input consists of the matrix dimensions and the target string, while the output is a boolean value indicating the result.
Goldman Sachs
November 26, 2025124
12
182 solved
Given a 2D matrix of characters and a string, determine if the string can be formed as a subsequence by traversing the matrix in a top-to-bottom and left-to-right manner. The function should return true if the string can be constructed as a subsequence from the matrix, and false otherwise. The input consists of the matrix dimensions and the target string, while the output is a boolean value indicating the result.
Goldman Sachs 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
- Quickly identify the optimal approach and its theoretical basis
- Handle complex algorithm design with multiple interacting components
- Write concise, elegant code under time pressure
- Prove correctness of your approach and discuss alternative solutions
- Optimize beyond the obvious: discuss constant factor improvements
- Address follow-up variations and explain how the solution generalizes
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 optimize the space complexity of your solution?
- How would you test this solution thoroughly?
- How would your solution change if the input was sorted?
- How would you parallelize this solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires us to determine if a given string can be formed as a subsequence by traversing a 2D matrix of characters from top to bottom and left to right. This means that we can only move in ...
Approach
- Initialize: Start from the top-left corner of the matrix (0,0) and the first character of the target string.
- DFS Function: Create a recursive DFS function that takes the current positio...
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