算法——希尔排序

希尔排序：

package com.algorithm.sort;

import java.util.Scanner;

/**
 * 希尔排序：基于插入排序的快速排序
 */
public class Shell {
    /**
     * 排序代码
     * @param a
     */
    public static void sort(Comparable[] a) {
        //升序排列
        int N = a.length;
        int h = 1;
        while(h < N/3) {
            h = 3*h+1;
        }
        while(h >= 1) {
            //将数组变为h有序
            for(int i=h; i<N; i++) {
                for(int j=i; j>=h&&less(a[j],a[j-h]);j-=h) {
                    exch(a,j,j-h);
                }
            }
            h = h/3;
        }
    }
    /**
     * 
     * @param v
     * @param w
     * @return
     */
    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;
    }
    /**
     * 打印数组
     * @param a
     */
    private static void show(Comparable[] a) {
        for(int i = 0; i<a.length;i++) {
            System.out.print(a[i] + "  ");
        }
    }
    /**
     * 判断数组原始是否有序
     * @param a
     * @return
     */
    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 = new String[3];
//        Scanner in = new Scanner(System.in);
//        for(int i=0;i<a.length;i++) {
//            a[i] = in.next();
//        }
        String[] a = {"d","g","c","b","f","e","a"};
        sort(a);
        System.out.println(isSorted(a));
        show(a);
    }

}