2.1.1

import edu.princeton.cs.algs4.*;

public class Selection
{
    public static void sort(Comparable[] a)
    {
        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;
            StdOut.print(i + " " + min + "\t");
            for(int t = 0; t < a.length; t++)
                StdOut.print(a[t] + " ");
            StdOut.println();
            
            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 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)
    {
        //输入 E A S Y Q U E S T I O N
        String[] a = In.readStrings();//CTRL + d
        sort(a);
        assert isSorted(a);
        show(a);
    }
}