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1593. Split a String Into the Max Number of Unique Substrings

Difficulty Topics

Description

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.

 

Example 1:

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.

Example 2:

Input: s = "aba"
Output: 2
Explanation: One way to split maximally is ['a', 'ba'].

Example 3:

Input: s = "aa"
Output: 1
Explanation: It is impossible to split the string any further.

 

Constraints:

  • 1 <= s.length <= 16

  • s contains only lower case English letters.

Solution

split-a-string-into-the-max-number-of-unique-substrings.py
class Solution:
    def maxUniqueSplit(self, S: str) -> int:
        def backtrack(S, seen):
            res = 0
            for i in range(1, len(S)+1):
                c = S[:i]
                if c not in seen:
                    seen.add(c)
                    res = max(res, 1 + backtrack(S[i:], seen))
                    seen.remove(c)

            return res

        seen = set()
        return backtrack(S, seen)