Consider a 2 - D array A[ ][ ] which represents a matrix having same no. of rows and columns. Let the no. of rows be n then the size of the matrix that the array A[ ][ ] represents is n×n. The array elements are such that the value at each location is equivalent to the difference between the column number and the row number. It is represented as follows : A[p][q] = p - q, where 1≤p≤n and 1≤q≤n. What would be the sum of the elements of the matrix representation of array A[ ][ ]?