Count kth largest element in interval list
Last updated: April 1, 2026
Quick Overview
Given a list of intervals, each defined by a pair of integers representing its start and end points, write a function to determine the k-th largest interval based on its length. The function should take in a list of intervals and an integer k, and return the length of the k-th largest interval. If k is greater than the number of intervals, return -1.
Compass
April 1, 20260
14
3,059 solved
Given a list of intervals, each defined by a pair of integers representing its start and end points, write a function to determine the k-th largest interval based on its length. The function should take in a list of intervals and an integer k, and return the length of the k-th largest interval. If k is greater than the number of intervals, return -1.
This coding problem is frequently asked during Phone Screen at Compass. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Compass 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
- How would you test this solution thoroughly?
- What happens if the input contains duplicates?
- What is the worst-case input for your solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
The problem requires us to find the k-th largest interval based on its length from a list of intervals. The specific pattern that applies here is sorting, as we need to compare the lengths of the inte...
Approach
- First, calculate the lengths of each interval by subtracting the start from the end point. For example, for the intervals [(1, 4), (2, 6), (5, 8)], the lengths would be [3, 4, 3].
- Next, sort t...
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