use same random array for each sort

Question

I'm trying to make it so i generate a random array but implement just that one same array(in the random order) with different sorts. I have:

public static void main(String[] args)
{
    int[] array = new int[10];
    for(int i = 0; i < array.length; i++) {
        array[i] = (int)(Math.random()*100);}

    System.out.println("\nBefore Bubble Sort: ");
    for (int element : array)
        System.out.print(element + "  "); 

    bubbleSort(array);


    System.out.println("After Bubble Sort: "); 
    for (int element : array)
        System.out.print(element + "  ");
    System.out.println("\n");

    System.out.println("\nBefore Insertion Sort: ");
    for (int element : array)
        System.out.print(element + "  "); 

    insertionSort(array);


    System.out.println("After Insertion Sort: "); 
    for (int element : array)
        System.out.print(element + "  ");
    System.out.println("\n");
}

With corresponding code for the sorts (I will post them if necessary). Its output is:

Array Before Bubble Sort: 
2 64 27 1 81 60 72 6 9 82
Array After Bubble Sort: 
1 2 6 9 27 60 64 72 81 82 

Array Before Insertion Sort: 
1 2 6 9 27 60 64 72 81 82 
Array After Insertion Sort: 
1 2 6 9 27 60 64 72 81 82

I want this array 2 64 27 1 81 60 72 6 9 82 to be in the before insertion line as well. The sorted array from bubble sort is just being put in the insertion sort so it's not doing anything. I think I need to make a method for the random array and call that with each sort? How would I do that? Or any other solution I'd appreciate. I will edit with more information if needed.

Use System.arraycopy to copy your array into a 'fixture', and copy that fixture back before each sort execution. — M. le Rutte
– M. le Rutte, Commented Oct 18, 2017 at 14:42

Ted Hopp · Accepted Answer · 2017-10-18 15:11:38Z

2

Clone or copy the array before each sort and pass the clone to the sort routine. You can use array.clone() or Arrays.copyOf(array, array.length) to make the copy.

public static void main(String[] args)
{
 int[] array = new int[10];
  for(int i = 0; i < array.length; i++) {
   array[i] = (int)(Math.random()*100);}

   System.out.println("\nBefore Bubble Sort: ");
    for (int element : array)
      System.out.print(element + "  "); 

   int[] sorted = array.clone();
   bubbleSort(sorted);


   System.out.println("After Bubble Sort: "); 
    for (int element : sorted)
      System.out.print(element + "  ");
      System.out.println("\n");

   System.out.println("\nBefore Insertion Sort: ");
    for (int element : array)
        System.out.print(element + "  "); 

    sorted = array.clone();
    insertionSort(sorted);


    System.out.println("After Insertion Sort: "); 
    for (int element : sorted)
        System.out.print(element + "  ");
    System.out.println("\n");
}

edited Oct 18, 2017 at 15:11

answered Oct 18, 2017 at 14:42

Ted Hopp

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2 Comments

vee Over a year ago

Ok thank you this works. However it seems other than bubble sort, when i try to count comparisons and swaps, its counted as 0 swaps for insertion sort. So it's "magically" getting sorted without swapping and just printing out the sorted list. Do you know why?

Ted Hopp Over a year ago

@vee - I suspect you aren't re-cloning the array. See my updated answer, where I replaced the // etc. with explicit code.

alseether · Accepted Answer · 2018-05-11 08:28:29Z

0

You should make a copy of initial array in order to maintain the same data as original.

edited May 11, 2018 at 8:28

user9775194

answered Oct 18, 2017 at 14:42

alseether

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