算法 第四版 2.3.5

package Cap2_3;

import edu.princeton.cs.introcs.StdRandom;
import Cap2_1.sortTemplate;

public class Quick3way extends sortTemplate{

	public static void sort(Comparable[] a){
		StdRandom.shuffle(a);
		sort(a, 0, a.length-1);
	}
	public static void sort(Comparable[] a, int lo, int hi){
		if(hi <= lo) return;
		int lt = lo, i = lo + 1, gt = hi;
		Comparable v = a[lo];
		while(i <= gt){
			show(a);
			int cmp = a[i].compareTo(v);
			if      (cmp<0) exch(a, i++, lt++);
			else if (cmp>0) exch(a, i, gt--);
			else            i++;
		}
		sort(a, lo, lt-1);
		sort(a, gt+1, hi); //重复部分不用管了;	
	}
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		String a = "AAAAAAAAABBBBBBBBBBB";
		String[] b = a.split("");
		StdRandom.shuffle(b);
		sort(b);
//		show(b);
	}

}