Two Pointers on graph
Last updated: November 17, 2025
Quick Overview
Given a directed graph represented as an adjacency list, implement the two pointers technique to find the shortest path between two nodes. Your solution should return the path as a list of nodes, or indicate if no path exists. The input will consist of the graph and the start and end nodes, while the output should be the shortest path or an empty list if unreachable.
Cruise
November 17, 2025186
11
1,362 solved
Given a directed graph represented as an adjacency list, implement the two pointers technique to find the shortest path between two nodes. Your solution should return the path as a list of nodes, or indicate if no path exists. The input will consist of the graph and the start and end nodes, while the output should be the shortest path or an empty list if unreachable.
Coding interviews at Cruise 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
- Can you optimize the space complexity of your solution?
- What is the worst-case input for your solution?
- How would you parallelize this solution?
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Problem Analysis
The problem requires finding the shortest path between two nodes in a directed graph represented as an adjacency list. The two pointers technique is not directly applicable in this context; instead, w...
Approach
- Input Validation: Check if the graph is empty or if the start or end nodes are not present in the graph. If any of these checks fail, return an empty list.
- Initialize Data Structures: ...
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