Pakkaus

import java.util.Scanner;

public class Teht1 {

    public static void main(String[] args) {

        Scanner lukija = new Scanner(System.in);
        String input = lukija.nextLine();

        String mj = "";
        String lj = "";
        String output = "";
        boolean v = false;

        for (int i = 0; i < input.length(); i++) {

            char m = input.charAt(i);

            if (Character.isDigit(m)) {

                if (v) {
                    v = false;
                    
                    
//                    for (int j = 0; j < Integer.parseInt(lj); j++) {
//                        output += mj;
//                    }
                    
                    output += new String(new char[Integer.parseInt(lj)]).replace("\0", mj);

                    lj = "";
                }

                lj += m;
            } else {

                if (!v) {
                    v = true;
                    mj = "";
                }

                mj += m;
            }

        }

        for (int j = 0; j < Integer.parseInt(lj); j++) {
            output += mj;
        }

        System.out.println(output);

    }

}

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: TIME LIMIT EXCEEDED

Test 12

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 13

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 14

Group: 3

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: ACCEPTED