Count minimum cost in matrix

Last updated: August 23, 2025

Quick Overview

Count the number of minimum cost in the given matrix.

Optiver
Coding & Algorithms
Software Engineer
Optiver
August 23, 2025
Software Engineer
Phone Screen
Coding & Algorithms
Hard

129

8

2,552 solved


Count the number of minimum cost in the given matrix.

Optiver 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
  • Quickly identify the optimal approach and its theoretical basis
  • Handle complex algorithm design with multiple interacting components
  • Write concise, elegant code under time pressure
  • Prove correctness of your approach and discuss alternative solutions
  • Optimize beyond the obvious: discuss constant factor improvements
  • Address follow-up variations and explain how the solution generalizes
Key Topics to Cover
Dynamic programming and memoization
Binary search and divide and conquer
Tree structures and recursion
Graph algorithms and traversal
Hash maps and frequency counting
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
  • How would you parallelize this solution?
  • How would you modify your solution to handle streaming input?
  • Can you solve this in a single pass?
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