Greedy on graph
Last updated: February 22, 2026
Quick Overview
Given a weighted, directed graph, implement a greedy algorithm to find the minimum spanning tree. Your function should take the graph as input in the form of an adjacency list and return the edges that form the minimum spanning tree, along with their total weight.
MongoDB
February 22, 202673
14
4,455 solved
Given a weighted, directed graph, implement a greedy algorithm to find the minimum spanning tree. Your function should take the graph as input in the form of an adjacency list and return the edges that form the minimum spanning tree, along with their total weight.
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
- 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
- What if the input doesn't fit in memory?
- Can you solve this in a single pass?
- How would you modify your solution to handle streaming input?
Sharpen Your Skills on Codemia
Practice similar problems with our interactive workspace, get AI feedback, and track your progress.
Practice DSA ProblemsSample Answer
Problem Analysis
To solve the problem of finding the minimum spanning tree (MST) in a weighted, directed graph, we can apply Prim's algorithm, which is a greedy algorithm. The reason for using Prim's algorithm here is...
Approach
- Initialization: Start with an arbitrary node as the initial vertex of the MST. Use a priority queue (min-heap) to keep track of the edges connected to the MST.
- Edge Selection: Continuou...
Submit Your Answer
