/* ArrayExp.java -- Array example program
   by Craig Persiko for CS 111A

   Inputs a series of numbers into an array, sorts them,
   and outputs them.
*/

import java.util.Scanner;


class ArrayExp
{
  public static void main(String[] args)
  {
    Scanner scan = new Scanner(System.in);
    int[] nums;  // array reference variable

    int idx, numEntries, idxSmall;

    System.out.print("How many numbers do you want to enter? ");
    numEntries = scan.nextInt();

    // allocate the array, now that we know its size:

    nums = new int[numEntries];

    System.out.println("Enter your numbers (integers), separated by spaces or returns:");

    for (idx = 0; idx < numEntries; idx++)
    {
      nums[idx] = scan.nextInt();
    }

    // now sort the array using Selection Sort:

    for(int i = 0; i < numEntries - 1; i++)
    {
      idxSmall = indexOfSmallest(nums, i, numEntries-1);
      // make sure we didn't get -1 above.

      // in fact, no need to swap if idx == i either

      // (and idxSmall can't be < i since we use i above)

      if(idxSmall > i)
        swapValues(nums, idxSmall, i);
    }

    // output the array:

    System.out.println("In sorted order, the numbers you entered are:");

    System.out.print(nums[0]); // output first value

    // output rest of array with commas:

    for (idx = 1; idx < numEntries; idx++)
      System.out.print(", " + nums[idx]);
    System.out.println();
  }

  // return the index of the smallest int in the array a

  // between startIndex and endIndex (inclusive).

  // return -1 if there are no elements in the array after startIndex.

  private static int indexOfSmallest(int[] a, int startIndex, int endIndex)
  {
    if(a == null || a.length <= startIndex)
      return -1;

    int indexOfMin = startIndex; // initialize min so we can compare and find smallest value.


    for (int i = startIndex + 1; i <= endIndex; i++)
    {
      if(a[i] < a[indexOfMin])  // if we find a smaller number than the min

        indexOfMin = i;         // then this is the new min.

    }

    return indexOfMin;
  }

  // Exchange a[p1] and a[p2].  Because we can't pass an int by reference,

  // we must pass the array into the function to make the changes stick.

  private static void swapValues(int[] a, int p1, int p2)
  {
      int temp = a[p1];
      a[p1] = a[p2];
      a[p2] = temp;
  }
}

/*  Sample Output:

-bash-3.2$ java ArrayExp
How many numbers do you want to enter? 5
Enter your numbers (integers), separated by spaces or returns:
1 2 5 0 7
In sorted order, the numbers you entered are:
0, 1, 2, 5, 7
-bash-3.2$ java ArrayExp
How many numbers do you want to enter? 6
Enter your numbers (integers), separated by spaces or returns:
3 8 1
6 -6 23
In sorted order, the numbers you entered are:
-6, 1, 3, 6, 8, 23
-bash-3.2$ java ArrayExp
How many numbers do you want to enter? 3
Enter your numbers (integers), separated by spaces or returns:
6 82 13 1
In sorted order, the numbers you entered are:
6, 13, 82

*/