Greedy on linked list
Last updated: November 8, 2025
Quick Overview
Given a singly linked list, implement a function that rearranges the nodes in a greedy manner to maximize the sum of the values of the nodes at even indices after reordering. The function should take the head of the linked list as input and return the head of the modified linked list.
Spotify
November 8, 202532
14
977 solved
Given a singly linked list, implement a function that rearranges the nodes in a greedy manner to maximize the sum of the values of the nodes at even indices after reordering. The function should take the head of the linked list as input and return the head of the modified linked list.
Coding interviews at Spotify 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
- What if the input doesn't fit in memory?
- What is the worst-case input for your solution?
- How would you parallelize this solution?
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Problem Analysis
To maximize the sum of the values of the nodes at even indices in a linked list after rearranging them, we can identify that the underlying pattern is greedy. The greedy approach applies here beca...
Approach
- Extract Values: Traverse the linked list to extract all node values into a list. For example, for the list 3 -> 1 -> 4 -> 2, the values would be [3, 1, 4, 2].
- Sort Values: Sort the ext...
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