Validate linked list complete
Last updated: June 13, 2026
Quick Overview
Given a singly linked list, write a function to determine if the linked list is complete, meaning that all nodes are connected and there are no cycles. The function should return a boolean value: `true` if the linked list is complete and `false` otherwise.
SpaceX
June 13, 20264
11
3,542 solved
Given a singly linked list, write a function to determine if the linked list is complete, meaning that all nodes are connected and there are no cycles. The function should return a boolean value: `true` if the linked list is complete and `false` otherwise.
Coding interviews at SpaceX 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
- Identify the correct data structure and algorithm for the problem
- Write clean, bug-free code with proper variable naming
- Analyze time and space complexity correctly
- Handle basic edge cases (empty input, single element)
- Communicate your thought process while coding
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 test this solution thoroughly?
- What is the worst-case input for your solution?
- Can you solve this in a single pass?
- How would your solution change if the input was sorted?
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Problem Analysis
To determine if a singly linked list is complete (i.e., all nodes are connected and there are no cycles), we can use the Floyd's Cycle Detection Algorithm, also known as the Tortoise and Hare ...
Approach
- Initialize two pointers:
slowandfast. Set both to the head of the linked list. - Traverse the list using a while loop:
- Move
slowone step forward (i.e.,slow = slow.next). - Move...
- Move
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