Please describe algorithm, give pseudocode, argue correctness and given best upper bound running time.

2. (25 points) Let S, S' be two sequences of symbols from some alphabet with lengths n,m respectively. Give an efficient algorithm that decides whether S' is a subsequence of S. A subsequence of a sequence S = $1$2 ... Sn is any subset of the symbols in S taken in order, that is, it has the form Si Siz ... Sik, where 1