Implement Skip List with with follow-up
Last updated: March 24, 2026
Quick Overview
Implement a Union Find data structure that supports insert, delete, and lookup operations in O(1) time.
Notion
March 24, 202610
5
4,099 solved
Implement a Union Find data structure that supports insert, delete, and lookup operations in O(1) time.
Coding interviews at Notion 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 test this solution thoroughly?
- How would you modify your solution to handle streaming input?
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Problem Analysis
The problem requires implementing a Union-Find data structure that supports O(1) time complexity for insert, delete, and lookup operations. This data structure is ideal for managing disjoint sets and ...
Approach
- Data Structure Setup: Create a class
UnionFindthat will have a dictionary to map elements to their parents and another dictionary to track the size (or rank) of each set. - **Insert Operati...
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