Count minimum cost in binary tree

Last updated: August 13, 2025

Quick Overview

Count the number of kth largest element in the given matrix.

Brex
Coding & Algorithms
Software Engineer
Brex
August 13, 2025
Software Engineer
Phone Screen
Coding & Algorithms
Medium

141

15

1,669 solved


Count the number of kth largest element in the given matrix.

Brex uses this problem in the Phone Screen to evaluate your algorithmic thinking. They expect you to discuss multiple approaches, analyze trade-offs between them, and implement the optimal solution with clean, readable code.

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
Time and space complexity analysis
Hash maps and frequency counting
Data structure selection and trade-offs
Graph algorithms and traversal
Edge cases and input validation
How to Approach This
  1. Clarify input constraints and edge cases before writing code.
  2. Walk through your approach verbally and confirm with the interviewer before coding.
  3. Start with a brute force solution, then optimize. Mention time and space complexity.
  4. Test your solution with examples, including edge cases like empty input or duplicates.
  5. 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?
  • Can you optimize the space complexity of your solution?
  • How would you parallelize this solution?
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