Anti-diagonal sums
Your task
Given an R x C integer matrix, an anti-diagonal is the set of cells (i, j) sharing the same value of i + j. Return a list giving the sum of each anti-diagonal, ordered from the top-left band (i+j = 0) through the bottom-right band (i+j = R+C-2). The matrix has at least one row and one column. Values may be negative.
Examples
diagonal_band_sums(grid: list[list[int]]) -> list[int]Example 1
Input
diagonal_band_sums([[1, 2, 3], [4, 5, 6], [7, 8, 9]])Output
[1, 6, 15, 14, 9]