Pakkaus

//-----------------------------------------------------------
//  Tää on kaikki kaunista koodia, sä vaan luet tätä väärin
//-----------------------------------------------------------
//
//
//okei onhan tää ihan täyttä kuraa D:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.lang.reflect.Field;
//import java.io.PrintWriter;
//import java.util.Scanner;
import java.util.StringTokenizer;

public class Teht1 {

    public static void main(String[] args) throws NoSuchFieldException, IllegalArgumentException, IllegalAccessException {

//        Scanner lukija = new Scanner(System.in);
//        String input = lukija.nextLine();
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader lukija = new InputReader(inputStream);
//        PrintWriter out = new PrintWriter(outputStream);

        String input = lukija.next();

//        String mj = "";
//        String lj = "";
        StringBuilder op = new StringBuilder();
        StringBuilder mj = new StringBuilder();
        StringBuilder lj = new StringBuilder();
        boolean v = false;

//        for (int i = 0; i < input.length(); i++) {
//
//            char m = input.charAt(i);
//
//            if (Character.isDigit(m)) {
//
//                if (v) {
//                    v = false;
//
//                    output += new String(new char[Integer.parseInt(lj)]).replace("\0", mj);
//
//                    lj = "";
//                }
//
//                lj += m;
//            } else {
//
//                if (!v) {
//                    v = true;
//                    mj = "";
//                }
//
//                mj += m;
//            }
//
//        }
        final Field field = String.class.getDeclaredField("value");
        field.setAccessible(true);

        final char[] chars = (char[]) field.get(input);
        final int len = chars.length;
        for (int i = 0; i < len; i++) {

            char m = input.charAt(i);

            if (Character.isDigit(m)) {

                if (v) {
                    v = false;

//                    output += new String(new char[Integer.parseInt(lj)]).replace("\0", mj);
                    op.append(new String(new char[Integer.parseInt(lj.toString())]).replace("\0", mj));
                    
                    lj.setLength(0);
                }

                lj.append(m);
            } else {

                if (!v) {
                    v = true;
                    mj.setLength(0);
                }

                mj.append(m);
            }

        }

        op.append(new String(new char[Integer.parseInt(lj.toString())]).replace("\0", mj));

        System.out.println(op);

    }
}

class InputReader {

    public BufferedReader reader;
    public StringTokenizer tokenizer;

    public InputReader(InputStream stream) {
        reader = new BufferedReader(new InputStreamReader(stream));
        tokenizer = null;
    }

    public String next() {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken();
    }

    public int nextInt() {
        return Integer.parseInt(next());
    }

}

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