Merge K Sorted grids
Last updated: February 18, 2026
Quick Overview
Given two sorted arrays, merge them into a single sorted result.
MongoDB
Coding & Algorithms
Software Engineer
MongoDB
February 18, 2026Software Engineer
Phone Screen
Coding & Algorithms
Easy
60
14
3,595 solved
Given two sorted arrays, merge them into a single sorted result.
Coding interviews at MongoDB 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
- Identify the correct data structure and algorithm for the problem
- Write clean, bug-free code with proper variable naming
- Analyze time and space complexity correctly
- Handle basic edge cases (empty input, single element)
- Communicate your thought process while coding
Key Topics to Cover
Time and space complexity analysis
Data structure selection and trade-offs
Sorting and searching
Edge cases and input validation
Binary search and divide and conquer
Graph algorithms and traversal
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?
- Can you solve this iteratively instead of recursively (or vice versa)?
- 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 grids (or arrays), we can apply the min-heap (priority queue) approach. This is effective because we want to efficiently pull the smallest element from multiple sorted lists. Eac...
Approach
- Initialize a Min-Heap: Start by creating a min-heap.
- Insert First Elements: For each of the K grids, insert the first element along with its grid index and element index into the min-he...
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