4. (12 pts.) Skip List Sorting: Let A[1..n] be an array of positive integers, and let r be the difference between the largest and the smallest value in A. (a) (2pt) Consider the array (5,3,3,7,11,7,7,1,7,3). What is r ? (b) (8pt) Describe an algorithm to sort A. Your algorithm should run in time O(n+r). (Hint: Recall what I said in lecture on 1/24 about what to do to sort a bag of cash) (c) (2pt) When r is constant with respect to n, then this algorithm is faster than the (nlogn) lower bound we covered in class. Explain why the sorting lower bound that we covered in lecture does not apply here