Count minimum cost in grid
Last updated: January 10, 2026
Quick Overview
Given a grid represented by a 2D matrix where each cell contains a non-negative integer cost, write a function to calculate the minimum cost to travel from the top-left corner to the bottom-right corner of the grid, moving only down or right. The function should return the minimum cost as an integer.
HashiCorp
January 10, 202641
14
4,347 solved
Given a grid represented by a 2D matrix where each cell contains a non-negative integer cost, write a function to calculate the minimum cost to travel from the top-left corner to the bottom-right corner of the grid, moving only down or right. The function should return the minimum cost as an integer.
Coding interviews at HashiCorp 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
- 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
- Can you solve this in a single pass?
- What is the worst-case input for your solution?
- How would your solution change if the input was sorted?
- What happens if the input contains duplicates?
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Problem Analysis
This problem is fundamentally about finding the minimum path cost in a grid, which is a classic dynamic programming problem. We can only move down or right, which simplifies our traversal options. The...
Approach
- Initialize a 2D list
dpof the same dimensions as the input grid, wheredp[i][j]will store the minimum cost to reach cell(i, j). - Set the starting point
dp[0][0]togrid[0][0].
3....
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