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// Exercise 2.1.24, 2.1.25 (Solution published at http://algs4.cs.princeton.edu/)
package algs21;
import stdlib.*;

public class XInsertionX {

  public static <T extends Comparable<? super T>> void sort(T[] a) {
    int N = a.length;

    // put smallest element in position to serve as sentinel
    for (int i = N-1; i > 0; i--)
      if (less(a[i], a[i-1])) exch(a, i, i-1);

    // insertion sort with half-exchanges
    for (int i = 2; i < N; i++) {
      T v = a[i];
      int j = i;
      while (less(v, a[j-1])) {
        a[j] = a[j-1];
        j--;
      }
      a[j] = v;
    }

    assert isSorted(a);
  }


  /* *********************************************************************
   *  Helper sorting functions
   ***********************************************************************/

  // is v < w ?
  private static <T extends Comparable<? super T>> boolean less(T v, T w) {
    if (COUNT_OPS) DoublingTest.incOps ();
    return v.compareTo(w) < 0;
  }

  // exchange a[i] and a[j]
  private static void exch(Object[] a, int i, int j) {
    if (COUNT_OPS) DoublingTest.incOps ();
    Object swap = a[i];
    a[i] = a[j];
    a[j] = swap;
  }


  /* *********************************************************************
   *  Check if array is sorted - useful for debugging
   ***********************************************************************/
  private static <T extends Comparable<? super T>> boolean isSorted(T[] a) {
    for (int i = 1; i < a.length; i++)
      if (less(a[i], a[i-1])) return false;
    return true;
  }

  // print array to standard output
  private static <T> void show(T[] a) {
    for (T element : a) {
      StdOut.println(element);
    }
  }

  // test code
  private static boolean COUNT_OPS = false;
  public static void main(String[] args) {
    StdIn.fromString ("S O R T E X A M P L E");
    //StdIn.fromFile ("data/tiny.txt");
    StdIn.fromFile ("data/words3.txt");
    String[] a = StdIn.readAllStrings();
    Insertion.sort(a);
    show(a);
    COUNT_OPS = true;
    DoublingTest.run (2000, 5, N -> ArrayGenerator.integerRandomUnique (N),          (Integer[] x) -> sort (x));
    DoublingTest.run (2000, 5, N -> ArrayGenerator.integerRandom (N, 2),             (Integer[] x) -> sort (x));
    DoublingTest.run (2000, 5, N -> ArrayGenerator.integerPartiallySortedUnique (N), (Integer[] x) -> sort (x));

  }

}