Count shortest distance in graph
Last updated: February 2, 2026
Quick Overview
Given a weighted, undirected graph represented as an adjacency list, write a function to calculate the shortest distance between two specified nodes. The function should take the graph, the starting node, and the target node as inputs, and return the shortest distance as an integer. If there is no path between the nodes, return -1.
Apple
February 2, 202687
13
2,160 solved
Given a weighted, undirected graph represented as an adjacency list, write a function to calculate the shortest distance between two specified nodes. The function should take the graph, the starting node, and the target node as inputs, and return the shortest distance as an integer. If there is no path between the nodes, return -1.
Apple uses this problem in the Take-home Project 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
- 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
- How would you modify your solution to handle streaming input?
- How would you parallelize this solution?
- Can you optimize the space complexity of your solution?
- Can you solve this in a single pass?
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Practice DSA ProblemsSample Answer
Problem Analysis
This problem requires finding the shortest distance between two nodes in a weighted, undirected graph. The most suitable algorithm for this task is Dijkstra's algorithm, which is specifically designed...
Approach
- Initialize Data Structures: Create a priority queue (min-heap) to store nodes and their cumulative distances from the starting node. Also, maintain a dictionary to track the shortest distances ...
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