Write a function that accepts a 1-dimensional array of integers, a[], and two integers ROWS and COLS. The function copies the elements into a 2D array with the specified numbers of ROWS and COLS. Element [0] of the input array goes to element [0][0] of the 2D array. Element [1] of the input array goes to element [0][1], and so on. In the resulting 2D array, return the sum of all the elements on and below the diagonal. (The diagonal are the elements for which row == column)