Implement Union Find with O(n) time
Last updated: November 6, 2025
Quick Overview
Implement a Stack data structure that supports insert, delete, and lookup operations in O(log n) time.
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Implement a Stack data structure that supports insert, delete, and lookup operations in O(log n) time.
Coding interviews at Pinterest 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?
- How would your solution change if the input was sorted?
- Can you solve this iteratively instead of recursively (or vice versa)?
- Can you optimize the space complexity of your solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires us to implement a Stack data structure that supports insert, delete, and lookup operations in O(log n) time. This suggests that we need a data structure that maintains order...
Approach
- Define the Stack Class: Create a class
Stackthat will utilize a BST as its underlying data structure. - Insert Operation: When inserting an element, we will add it to the BST. We need ...
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