2405. Optimal Partition of String

Given a string s, partition the string into one or more substrings such that the characters in each substring are unique. That is, no letter appears in a single substring more than once.

Return the minimum number of substrings in such a partition.

Note that each character should belong to exactly one substring in a partition.

 

Example 1:

Input: s = "abacaba"
Output: 4
Explanation:
Two possible partitions are ("a","ba","cab","a") and ("ab","a","ca","ba").
It can be shown that 4 is the minimum number of substrings needed.

Example 2:

Input: s = "ssssss"
Output: 6
Explanation:
The only valid partition is ("s","s","s","s","s","s").

 

Constraints:

• 1 <= s.length <= 105
• s consists of only English lowercase letters.

---

class Solution:
    def partitionString(self, s: str) -> int:
        ans=0
        exist=""
        for i in range(len(s)):
            if s[i] not in exist:
                exist+=s[i]
            else:
                ans+=1
                exist=s[i]
        return ans +1 if exist else ans