2 Pancake sorting Suppose you are given a stack of n pancakes of different sizes. You must sort the pancakes so that smaller pancakes are on top of larger pancakes. The only operation you can perform is a flip: insert a spatula under the top k pancakes, for some integer k between 1 and n, and flip them all over. 2.1 Describe an algorithm to sort an arbitrary stack of n pancakes using O(n) flips. Exactly how many flips does your algorithm perform in the worst case? 2.2 For every positive integer n, describe a stack of n pancakes where your algorithm from 2.1 requires N(n) flips to sort.