Selection.java

public class Selection
{
  public static void sort(Comparable[] a)
  {   // Sort a[] into increasing order.
      int N = a.length;
      for (int i = 0; i < N; i++)
      {
          int min = i;
          for (int j = i + 1; j < N; j++)
          {
            if (less(a[j], a[min])) min = j;
        }
          exch(a, i, min);
      }
  }

  private static boolean less(Comparable v, Comparable w)
  { return v.compareTo(w) < 0; }

  private static void exch(Comparable[] a, int i, int j)
  { Comparable t = a[i]; a[i] = a[j]; a[j] = t; }

  private static boolean isSorted(Comparable[] a)
  {
      for (int i = 1; i < a.length; i++)
          if (less(a[i], a[i - 1])) return false;
      return true;
  }

  private static void show(String[] a)
  {
      for (int i = 0; i < a.length; i++) StdOut.print(a[i] + " ");
      StdOut.println();
  }

  public static void main(String[] args)
  {
    String[] a = StdIn.readAllStrings();
    sort(a);
    assert isSorted(a);
    show(a);
  }
}