希尔排序

//希尔排序//希尔排序是基于插入排序的快速排序算法//希尔排序为了加快速度简单地改进了插入排序，交换不相邻的元素以对数组的局部进行排序，并最终用插入排序将局部有序的数组排序package Algorithms;import edu.princeton.cs.algs4.StdIn;import edu.princeton.cs.algs4.StdOut;public class P163_Shell {private P163_Shell(){}public static void sort(Comparable[] a){//将a[]按升序排列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++){//将a[i]插入到a[i-h],a[i-2*h],a[i-3*h]...之中for (int j = i; j >= h && less(a[j], a[j - h]); j -= h){exch(a, j, j - h);}}assert isHsorted(a, h);h /= 3;}assert isSorted(a);}// is v < w ?    private static boolean less(Comparable v, Comparable w) {        return v.compareTo(w) < 0;    }            // exchange a[i] and a[j]    private static void exch(Object[] a, int i, int j) {        Object swap = a[i];        a[i] = a[j];        a[j] = swap;    }        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;    }    // is the array h-sorted?    private static boolean isHsorted(Comparable[] a, int h) {        for (int i = h; i < a.length; i++)            if (less(a[i], a[i-h])) return false;        return true;    }    // print array to standard output    private static void show(Comparable[] a) {        for (int i = 0; i < a.length; i++) {            StdOut.println(a[i]);        }    }        public static void main(String[] args) {String[] a = StdIn.readAllStrings();P163_Shell.sort(a);show(a);}}