Validate grid symmetric
Last updated: June 3, 2026
Quick Overview
Given a 2D grid, write a function to determine if the grid is symmetric about its center. The function should return true if the grid is symmetric, meaning that it is identical when flipped both horizontally and vertically; otherwise, it should return false. The input will be a 2D list of integers, and the output should be a boolean value.
Goldman Sachs
June 3, 202612
8
3,465 solved
Given a 2D grid, write a function to determine if the grid is symmetric about its center. The function should return true if the grid is symmetric, meaning that it is identical when flipped both horizontally and vertically; otherwise, it should return false. The input will be a 2D list of integers, and the output should be a boolean value.
Goldman Sachs 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
- 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
- Can you optimize the space complexity of your solution?
- 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
To determine if a 2D grid is symmetric about its center, we need to check if each cell in the grid is equal to its corresponding cell when the grid is flipped both horizontally and vertically. This is...
Approach
We will implement the following algorithm:
- First, check if the grid is empty (edge case). If so, return True.
- Obtain the dimensions of the grid: n (rows) and m (columns).
- Loop through each ce...
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