/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
    public static void main(String[] args) {
 
        int[] a = new int[]{3, 2, 1};
        int[] b = new int[]{8, 9};
        int[] rMultiplicacion = multiplicar(a, b);
        toString(rMultiplicacion);
    }
 
    public static int[] multiplicar(int[] a, int[] b) {
        int[] r = new int[a.length + b.length + 1];
        for (int i = 0; i < r.length; i++) {
            r[i] = 0;
        }
 
        for (int i = a.length - 1; i >= 0; i--) {
            for (int j = b.length - 1; j >= 0; j--) {
                int mul = r[i + j] + (a[i] * b[j]);
                System.out.println("Case 1" + r[i + j] + " " + mul + " ");
                r[i + j] = mul % 10;
                System.out.println("Case 2" + r[i + j] + " " + mul + " ");
                r[i + j + 1] += mul / 10;
                System.out.println("Case 3" + r[i + j + 1] + " " + mul + " ");
            }
        }
        return r;
    }
 
    public static void toString(int[] a) {
        for (int i = a.length - 1; i >= 0; i--) {
            System.out.print(a[i]);
        }
        System.out.println();
    }
}

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