Merge K Sorted matrixs
Last updated: January 15, 2026
Quick Overview
Given k sorted linked lists, merge them into a single sorted result.
Cockroach Labs
Coding & Algorithms
Machine Learning Engineer
Cockroach Labs
January 15, 2026Machine Learning Engineer
Take-home Project
Coding & Algorithms
Medium
20
12
453 solved
Given k sorted linked lists, merge them into a single sorted result.
Coding interviews at Cockroach Labs 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
- 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
Time and space complexity analysis
Hash maps and frequency counting
Edge cases and input validation
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
- How would you test this solution thoroughly?
- How would you modify your solution to handle streaming input?
- What is the worst-case input for your solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
To merge k sorted linked lists efficiently, we can utilize a min-heap (or priority queue) which is a perfect fit for this problem as it allows us to always access the smallest element among multip...
Approach
- Initialization: Create a min-heap and a result list to store the merged output.
- Heap Population: Iterate through each of the k linked lists and add the head node of each list to the min-...
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