Count shortest distance in linked list
Last updated: August 16, 2025
Quick Overview
Given a singly linked list, write a function to count the number of nodes that are at the shortest distance from a specified target node. The function should take the head of the linked list and the target node's value as input, and return the count of nodes that have the minimum distance to the target node. The distance between nodes is defined as the number of edges in the path connecting them.
HubSpot
August 16, 2025106
9
3,520 solved
Given a singly linked list, write a function to count the number of nodes that are at the shortest distance from a specified target node. The function should take the head of the linked list and the target node's value as input, and return the count of nodes that have the minimum distance to the target node. The distance between nodes is defined as the number of edges in the path connecting them.
Coding interviews at HubSpot 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
- 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
- What is the worst-case input for your solution?
- Can you solve this in a single pass?
- What happens if the input contains duplicates?
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Problem Analysis
To solve the problem of counting the number of nodes that are at the shortest distance from a specified target node in a singly linked list, we can utilize a BFS (Breadth-First Search) approach. The B...
Approach
- Initialize: Start by creating a queue to perform BFS, and a hashmap to store distances of nodes from the target node. Also, keep track of the target node's position.
- BFS Traversal: From ...
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