you are given a list X$,$ which is a sequence composed of $0$s and $1$s$.$ the task is to compute the length of the longest subsequence within this array that alternates between $0$s and $1$s$.$

a subsequence is a sequnce that can be derived from the original array by deleting some or none of the elements, ensuring the order of the remeaining elements is maintained. na alternating subsequence is one where no two adjacent elements are the same. in simpler terms, the

elements of the subsequnce alternate between $0$ and $1$