Implement Skip List with with follow-up
Last updated: January 30, 2026
Quick Overview
Implement a Skip List data structure that supports insertion, deletion, and search operations in O(log n) time on average. The Skip List should allow for efficient traversal and maintain a sorted order of elements. Your implementation should include methods for inserting a new element, deleting an existing element, and searching for an element, with appropriate input and output handling.
Palo Alto Networks
January 30, 20266
12
4,298 solved
Implement a Skip List data structure that supports insertion, deletion, and search operations in O(log n) time on average. The Skip List should allow for efficient traversal and maintain a sorted order of elements. Your implementation should include methods for inserting a new element, deleting an existing element, and searching for an element, with appropriate input and output handling.
This coding problem is frequently asked during Take-home Project at Palo Alto Networks. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Palo Alto Networks expects candidates to write production-quality code, not just solve the puzzle.
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 is the worst-case input for your solution?
- Can you solve this iteratively instead of recursively (or vice versa)?
- What happens if the input contains duplicates?
- Can you optimize the space complexity of your solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
The Skip List is a probabilistic data structure that allows for efficient search, insertion, and deletion operations with average time complexity of O(log n). The key patterns utilized here are linked...
Approach
To implement a Skip List, we will define a node structure with multiple forward pointers, one for each level of the list. The Skip List will maintain a head node and use a random height generation to ...
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