Pakkaus

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 */
//package datatahti1;

import java.util.*;

/**
 *
 * @author ACER
 */
public class Datatahti1 {
static StringBuilder vv = new StringBuilder();
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        String merkkijono = input.nextLine();
       // String merkkijono = "999999a";
        StringBuilder vastaus;
        kvn kjn = kvn.emt;
        int numero = 1;
        StringBuilder vms = new StringBuilder();
        //int pituus = merkkijono.length();
        for (char merkki: merkkijono.toCharArray()) {

            if (Character.isDigit(merkki)) {

                if (kjn == kvn.kirjain) {

                    luuppi(vms, numero);
                    vms.setLength(0);

                }
                kjn = kvn.numero;
                vms.append(merkki);
            } else if (Character.isLetter(merkki)) {

                if (kjn == kvn.numero) {

                    numero = Integer.parseInt(vms.toString());
                    vms.setLength(0);

                }
                kjn = kvn.kirjain;
                vms.append(merkki);

            }

        }
        if (kjn == kvn.kirjain) {

            luuppi(vms, numero);

        }
        System.out.println(vv);
    }

    private enum kvn {

        numero, kirjain, emt
    }

    private static void luuppi(StringBuilder merkit, int toistot) {
        
        for (int i = 0; i < toistot; i++) {

            vv.append(merkit);

        }
    }
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 2

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: ACCEPTED

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: ACCEPTED

Test 14

Group: 3

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: ACCEPTED