Greedy on graph
Last updated: May 22, 2026
Quick Overview
Given a weighted, directed graph, implement a greedy algorithm to find the shortest path from a starting vertex to a target vertex. Your solution should return the total weight of the shortest path and the sequence of vertices traversed. Assume the graph is represented as an adjacency list, and handle cases where no path exists by returning an appropriate indicator.
HubSpot
May 22, 2026242
7
2,349 solved
Given a weighted, directed graph, implement a greedy algorithm to find the shortest path from a starting vertex to a target vertex. Your solution should return the total weight of the shortest path and the sequence of vertices traversed. Assume the graph is represented as an adjacency list, and handle cases where no path exists by returning an appropriate indicator.
This coding problem is frequently asked during Take-home Project at HubSpot. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. HubSpot expects candidates to write production-quality code, not just solve the puzzle.
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 is the worst-case input for your solution?
- Can you solve this iteratively instead of recursively (or vice versa)?
- What if the input doesn't fit in memory?
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Practice DSA ProblemsSample Answer
Problem Analysis
This problem is best solved using Dijkstra's algorithm, which is a greedy algorithm for finding the shortest paths in a weighted graph. The reason Dijkstra's algorithm is applicable here is that it ef...
Approach
- Initialization: Create a priority queue (min-heap) to hold vertices, initialized with the starting vertex and a distance of 0. Also, maintain a dictionary to record the shortest distance to eac...
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