Question 15
The memory of Bob's computer contains two interesting things: an array of integers and a virus. Each midnight the virus becomes active. It takes each array in memory and replaces it with a bunch of new arrays: one for each contiguous subarray of the original array.
For example, if today the memory contains a single array (1,2,1,3), tomorrow it will contain the following arrays: (1), (2), (1), (3), (1,2), (2, 1), (1, 3), (1,2,1), (2, 1,3), (1,2, 1, 3).
As another example, if today the memory contains a single array {(7,7)},tomorrow it will contain the following arrays: {(7), (7), (7,7)}, and the day after tomorrow it will contain the following arrays: {(7), (7), (7), (7), (7,7)}, and so on.
You are given Bob's original array A and the number of days D. Let be the sum of all elements of all arrays that will be in the memory of Bob's computer after D days. Our goal is to calculate . You may assume that the memory of Bob's computer is sufficiently large to accommodate all the arrays.
Based on the above data, answer the given subquestions.