3458. Select K Disjoint Special Substrings

Given a string s of length n and an integer k, determine whether it is possible to select k disjoint special substrings. A special substring is a substring where: - Any character present inside the substring should not appear outside it in the string. - The substring is not the entire string s. Note that all k substrings must be disjoint, meaning they cannot overlap. Return true if it is poss