Unique number of characters(Hashing)

 Unique number of characters(Hashing)

Problem Statement

Given a string s, your task is to find the total number of unique characters in a string.

import java.io.*; // for handling input/output

import java.util.*; // contains Collections framework

// don't change the name of this class

// you can add inner classes if needed

class Main {

    public static void main (String[] args) {

        Scanner sc =  new Scanner(System.in);

        HashSet<Character> hs = new HashSet<>();

        String str = sc.nextLine();

        int n = str.length();

        for(int i=0;i<n;i++){ //pick char by char 

            hs.add(str.charAt(i));

        }

        System.out.println(hs.size());

    }

}