Question
Given an m x n integer matrix and an integer `target`, return the number of non-empty submatrices (contiguous rectangular blocks) whose elements sum to exactly `target`. Values may be negative. m, n are up to 100. A brute force over all O(m^2 n^2) rectangles is too slow; collapse one dimension with prefix sums and use the subarray-sum-equals-k hashing trick on the other.
num_submatrix_sum_target(matrix: list[list[int]], target: int) → int[[[0,1,0],[1,1,1],[0,1,0]],0]out4State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.
Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.