Consider the following variant of string alignment: given two strings x,y, and a positive integer L, nd all contiguous substrings of length at least L that are aligned (using no-ops = substituting a letter for itself) in some optimal alignment of x and y. Assume the costs of substitution, insertion, and deletion are given by constants csubs,cins,cdel, and that the cost of substituting a letter for itself is zero.

(a) Show that the output here contains at most O((nL)^3) substrings.

(b) Give an algorithm that solves this problem