ALGORITHM2.2 Insertion sort

import edu.princeton.cs.algs4.*;

public class Insertion
{
    public static void sort(Comparable[] a)
    {
        int N = a.length;
        for(int i = 0; i < N; i++)
        {
            for(int j = i; j > 0 && less(a[j], a[j-1]); j--)
                exch(a, j, j-1);
        }
    }
    
    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 void show(Comparable[] a)
    {
        for(int i = 0; i < a.length; i++)
            StdOut.print(a[i] + " ");
        StdOut.println();
    }
    
    public static boolean isSorted(Comparable[] a)
    {
        for(int i = 1; i < a.length; i++)
            if(less(a[i], a[i-1])) return false;
        return true;
    }
    
    public static void main(String[] args)
    {
        String[] a = In.readStrings();//CTRL + d
        sort(a);
        assert isSorted(a);
        show(a);
    }
}