Envío 6151

Código

import java.util.HashMap;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String word = scanner.nextLine();
        char[] charArray = word.toCharArray();
        HashMap<Character, Boolean> memoization = new HashMap<>();
        
        for(int i=0; i<=charArray.length; i++){
            if(i == charArray.length){
                System.out.println("no");
                break;
            }
            
            if(!memoization.containsKey(charArray[i])){
                memoization.put(charArray[i], true);
            } else {
                System.out.println("yes");
                break;
            }
        }
    }
}