Your question is Absolute Difference of Diagonal Sums. Start with the requirements on the right.
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Workiva's reporting surfaces may represent a square set of aligned values as a matrix. Given a square matrix of integers, calculate the absolute difference between the sum of its primary diagonal and the sum of its secondary diagonal.
The primary diagonal runs from the top-left corner to the bottom-right corner. The secondary diagonal runs from the top-right corner to the bottom-left corner.
Implement diagonal_difference(matrix), where matrix is a non-empty n x n list of lists of integers. Return a single non-negative integer equal to abs(primary_sum - secondary_sum).
You may count the center cell in both diagonal sums when n is odd. It appears in both sums, so it does not affect their difference.
def diagonal_difference(matrix):