11. (a) Merging two sorted lists, one of length p and one of length q, into a single sorted list takes about p + q comparisons. Suppose we had n lists of length 10 and we wanted to merge them all into one sorted list. One way would be to merge the first with the second, and then this merged list with the third, and then this merged list with the fourth, etc. About how many comparisons would this take? (2 marks) Explain (without necessarily writing a detailed algorithm) how you could improve on this method by using a divide-and-conquer approach. Work out approximately how many comparisons this would take. [You may assume that n is a power of 2.) (6 marks) (b)