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

Seawolf

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.

1. class Solution:
   
2.     def maxUniqueSplit(self, s: str) -> int:
   
3.         def backtrack(s, hashset):
   
4.             max_val = 0
   
5.             
   
6.             for i in range(1, len(s) + 1):
   
7.                 curt = s[:i]
   
8.                
   
9.                 if curt not in hashset:
   
10.                     hashset.add(curt)
    
11.                     max_val = max(max_val, 1 + backtrack(s[i:], hashset))
    
12.                     hashset.discard(curt)
    
13.             
    
14.             return max_val
    
15.         
    
16.         return backtrack(s, set())

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