Count minimum cost in graph
Last updated: October 21, 2025
Quick Overview
Given a weighted directed graph represented as an adjacency list, write a function to calculate the minimum cost to traverse from a specified source node to a target node. The function should return the minimum cost as an integer, or -1 if there is no path from the source to the target.
Two Sigma
October 21, 202542
3
1,328 solved
Given a weighted directed graph represented as an adjacency list, write a function to calculate the minimum cost to traverse from a specified source node to a target node. The function should return the minimum cost as an integer, or -1 if there is no path from the source to the target.
Two Sigma uses this problem in the Phone Screen 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
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 modify your solution to handle streaming input?
- How would you test this solution thoroughly?
- Can you solve this in a single pass?
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Practice DSA ProblemsSample Answer
Problem Analysis
This problem requires finding the minimum cost to traverse from a source node to a target node in a weighted directed graph. The most suitable algorithm for this scenario is Dijkstra's algorithm, whic...
Approach
- Initialization: Create a priority queue to store nodes along with their cumulative costs. Use a dictionary to keep track of the minimum cost to reach each node, initializing the source node wit...
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