//ArrayLists.java
//Ivey Rao

import java.util.ArrayList;
public class ArrayLists
{
   public static void scaleByK(ArrayList<Integer> array)
   {
      ArrayList<Integer> mod = new ArrayList<>();
      for(int k=0; k<array.size();k++)
      {
         if(array.get(k) > 0)
         {
            for(int i=0; i<(array.get(k)); i++)
            {
               mod.add(array.get(k));
               //System.out.println("i: " +i); //to test
               //System.out.println("mod"+mod); //to test
            }
         }
      }
      array = mod;
   }

   public static void interleave(ArrayList<Integer> array1, ArrayList<Integer> array2)
   {
      int array2Count = 0;
         for(int i=1; i<array1.size()+array2.size()-2; i+=2)
         {
            array1.add(i, array2.get(array2Count));
            array2Count++;
            //System.out.println("array1"+array1); //to test
         }
      //System.out.println(
   }
}

//runner

//ArrayListsRunner.java
//Ivey Rao

import java.util.ArrayList;

public class ArrayListsRunner
{
   public static void main(String[]args)
   {
      //scaleByK() positive integer array test
      ArrayList<Integer> array = new ArrayList<>();
      array.add(1);
      array.add(2);
      array.add(3);
      System.out.println("array: "+array);
      ArrayLists.scaleByK(array);

      //scaleByK() negative & zero integer array test
      ArrayList<Integer> negatives = new ArrayList<>();
      negatives.add(0);
      negatives.add(-1);
      negatives.add(1);
      System.out.println("negatives: "+negatives);
      ArrayLists.scaleByK(negatives);

      //scaleByK() empty array test
      ArrayList<Integer> empty = new ArrayList<>();
      System.out.println("empty: "+empty);
      ArrayLists.scaleByK(empty);

      //interleave() test
      ArrayLists.interleave(array,negatives);
      //ArrayLists.interleave(array,empty);
   }
}