Merge K Sorted arrays
Last updated: January 7, 2026
Quick Overview
Given three sorted linked lists, merge them into a single sorted result.
Jane Street
Coding & Algorithms
Software Engineer
Jane Street
January 7, 2026Software Engineer
Onsite
Coding & Algorithms
Hard
9
11
2,283 solved
Given three sorted linked lists, merge them into a single sorted result.
Jane Street uses this problem in the Onsite 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
Data structure selection and trade-offs
Time and space complexity analysis
Sorting and searching
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 parallelize this solution?
- How would you modify your solution to handle streaming input?
- How would your solution change if the input was sorted?
- What if the input doesn't fit in memory?
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Practice DSA ProblemsSample Answer
Problem Analysis
To merge K sorted linked lists, we can utilize a min-heap (priority queue) as our primary data structure. The reason this approach is effective here is that we can always efficiently extract the s...
Approach
- Initialize a min-heap: Create a priority queue to keep track of the head nodes of the K linked lists.
- Insert the head nodes: Push the head node of each list into the min-heap.
- **Build...
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