Untitled

import java.util.*;

public class Solution {
    public int partitionString(String s) {
        Set<Character> seen = new HashSet<>();
        int partitions = 1;

        for (char c : s.toCharArray()) {
            if (seen.contains(c)) {
                // Start a new substring
                partitions++;
                seen.clear();
            }
            seen.add(c);
        }

        return partitions;
    }

    public static void main(String[] args) {
        Solution solution = new Solution();

        String s1 = "abacaba";
        System.out.println(solution.partitionString(s1)); // Output: 4

        String s2 = "ssssss";
        System.out.println(solution.partitionString(s2)); // Output: 6
    }
}