Matrix Transformation with Edge Cases | Dataford Interview Questions

Transform a 2D matrix from one input format into a specified output format, handling large test cases with tricky edge cases

Asked in the Round 2 - Technical Assessment stage. The candidate gave a garbled example: input [[1,2],[3,4]] -> output [[1,3],[4,10]]; this output is the 2D prefix sum matrix.

Implement prefix_sum_matrix(matrix). For each position (r, c), return the sum of all input values in the rectangle from (0, 0) through (r, c).

Contract

Input is a non-empty rectangular list of lists of integers. Return a matrix with the same dimensions.

Constraints

1 <= rows, columns <= 1000
rows * columns <= 10^6
-10^9 <= matrix[r][c] <= 10^9
The matrix is non-empty and rectangular

Function Signature

def prefix_sum_matrix(matrix):

Your question is Matrix Transformation with Edge Cases. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem