(a) Compute the prefix function pi for the pattern P = xyxyyxyy. Then, show how the KMP algorithm determines whether P occurs in the text string xyxxyxxyxyxyyxyyxyyxyxyyxyy. (b) We say that a sequence s' of characters is a subsequence of another sequence S if we can get S' by deleting certain characters in S. For example, the sequence abcd is a subsequence of cdaaacbbacccda. Design an algorithm that takes two sequences, S of n characters and S" of m characters, and decides in O(n + m) time whether s' is a subsequence of S