Given a string
s, return the maximum number of unique substrings that the given string can be split into.
You can split string
s into any list of non-empty substrings, where the concatenation of the substrings forms the original string. However, you must split the substrings such that all of them are unique.
A substring is a contiguous sequence of characters within a string.
Input: s = "ababccc" Output: 5 Explanation: One way to split maximally is ['a', 'b', 'ab', 'c', 'cc']. Splitting like ['a', 'b', 'a', 'b', 'c', 'cc'] is not valid as you have 'a' and 'b' multiple times.
Input: s = "aba" Output: 2 Explanation: One way to split maximally is ['a', 'ba'].
Input: s = "aa" Output: 1 Explanation: It is impossible to split the string any further.
1 <= s.length <= 16
s contains only lower case English letters.