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2405. Optimal Partition of String

Difficulty Topics

Description

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.

Solution

optimal-partition-of-string.py
class Solution:
    def partitionString(self, s: str) -> int:
        n = len(s)
        res = 1
        seen = set()

        for j, x in enumerate(s):
            if x in seen:
                seen.clear()
                res += 1

            seen.add(x)

        return res