// Source code example for "A Practical Introduction
// to Data Structures and Algorithm Analysis"
// by Clifford A. Shaffer, Prentice Hall, 1998.
// Copyright 1998 by Clifford A. Shaffer

// Sorting main function for testing correctness of sort algorithm.
// To use: <sortname> [+/-] <size_of_array> <threshold>
//  + means increasing values, - means decreasing value and no
//    parameter means random values;
// where <size_of_array> controls the number of objects to be sorted;
// and <threshold> controls the threshold parameter for certain sorts, e.g.,
//   cutoff point for quicksort sublists.

import java.io.*;

public class Sortmain {

static int THRESHOLD = 0;

static int ARRAYSIZE = 10000;
static void sort(Elem[] array) {
  Elem[] temp = new Elem[ARRAYSIZE];
  mergesort(array, temp, 0, array.length-1);
}

// Insertion Sort for subarrays: sort len elements from index start
static void inssort(Elem[] array, int start, int len) {
  for (int i=start+1; i<start+len; i++)        // Insert i'th record
    for (int j=i; (j>start) &&
                  (array[j].key()<array[j-1].key()); j--)
      DSutil.swap(array, j, j-1);
}
static void mergesort(Elem[] array, Elem[] temp, int l, int r) {
  int i, j, k, mid = (l+r)/2;  // Select the midpoint
  if (l == r) return;          // List has one element
  if ((mid-l) >= THRESHOLD) mergesort(array, temp, l, mid);
  else inssort(array, l, mid-l+1);
  if ((r-mid) > THRESHOLD) mergesort(array, temp, mid+1, r);
  else inssort(array, mid+1, r-mid);
  // Do the merge operation.  First, copy 2 halves to temp.
  for (i=l; i<=mid; i++) temp[i] = array[i];
  for (j=1; j<=r-mid; j++) temp[r-j+1] = array[j+mid];
  // Merge sublists back to array
  int a = temp[l].key(); int b = temp[r].key();
  for (i=l,j=r,k=l; k<=r; k++)
    if (a < b) { array[k] = temp[i++]; a = temp[i].key(); }
    else { array[k] = temp[j--]; b = temp[j].key(); }
}

// Main routine for sorting class driver
// This is the version for running timings
public static void main(String args[]) throws IOException {
  Assert.notFalse(args.length >= 1,
	  "Usage: Sortmain [+/-] <size> <threshold>");

  int i;
  int input = 0;
  int currarg = 0;
  if (args[currarg].charAt(0) == '+') { input = 1; currarg++; }
  else if (args[currarg].charAt(0) == '-') { input = -1; currarg++; }

  int ARRAYSIZE = Integer.parseInt(args[currarg++]);
  if (args.length > currarg)
	THRESHOLD = Integer.parseInt(args[currarg]);


  Elem[] array = new Elem[ARRAYSIZE];

  System.out.println("Input: " + input +
          ", size: " + ARRAYSIZE + ", threshold: " + THRESHOLD);

  if (input == -1)
    for (i=0; i<ARRAYSIZE; i++)
      array[i] = new IElem(ARRAYSIZE - i);  // Reverse sorted
  else if (input == 0)
    for (i=0; i<ARRAYSIZE; i++)
      array[i] = new IElem(DSutil.random(32003));  // Random
  else
    for (i=0; i<ARRAYSIZE; i++)
      array[i] = new IElem(i);              // Sorted

long time1 = System.currentTimeMillis();
  sort(array);
long time2 = System.currentTimeMillis();
System.out.println("Time is " + (time2-time1));

  System.out.println("Done sorting");

  // Double-check that the sort was correct
  for (i=1; i<ARRAYSIZE; i++)
    if (array[i].key() < array[i-1].key()) {
      System.out.println("OOPS -- bad sort algorithm!");
        for (int j=0; j<ARRAYSIZE; j++)
          System.out.print(array[j] + " ");
      System.out.println();
      break;
    }
  System.out.println("Sorting checked out OK.");

  System.in.read();
}

}