Merge K Sorted grids
Last updated: January 11, 2026
Quick Overview
Given two sorted strings, merge them into a single sorted result.
Pinterest
Coding & Algorithms
Software Engineer
Software Engineer
Technical Screen
Coding & Algorithms
Medium
6
9
173 solved
Given two sorted strings, merge them into a single sorted result.
Pinterest 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
- 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
Sorting and searching
Time and space complexity analysis
Common algorithm patterns (sliding window, two pointers, BFS/DFS)
Data structure selection and trade-offs
Tree structures and recursion
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 optimize the space complexity of your solution?
- How would you test this solution thoroughly?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires merging two sorted strings into a single sorted result. This problem can be analyzed using the Two Pointers technique because we have two sorted sequences and we need to combi...
Approach
- Initialize two pointers,
iandj, at the beginning of each string,s1ands2. - Create an empty result list to store the merged characters.
- Compare the characters pointed by
iand...
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