Sum of Diagonal Elements | Dataford Interview Questions

Sum the diagonal elements in an array

Asked in the Technical stage.

Given a square 2D integer array matrix, return the sum of its main diagonal, consisting of elements where the row and column indices are equal.

Function signature: def sum_diagonal(matrix):

Input: a non-empty square list of lists of integers. Output: one integer containing the main diagonal sum.

Example: matrix = [[1, 2], [3, 4]] returns 5. Example: matrix = [[5]] returns 5.

Constraints: 1 <= n <= 1000, len(matrix) == n, every row has length n, and each value is between -10^9 and 10^9.

def sum_diagonal(matrix):

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