数据结构与算法分析（Java语言描述）（4）—— 希尔排序

int n = arr.length;int h = 1;while(h < n/3){    h = h*3 + 1;}while(h >= 1){    for(int i = h; i < n; i++){        int temp = arr[i];        int j = i;        for( ; j >=h; j-=h){            if(arr[j-h].compareTo(temp) > 0){                arr[j] = arr[j-1];            }else{                break;            }        }        arr[j] = temp;    }    h /= 3;}

ShellSort.java

package com.algorithm.sort;public class ShellSort {    private ShellSort(){}    public static void sort(Integer[] arr){        int n = arr.length;        int h = 1;        // 计算 increment sequence: 1, 4, 13, 40, 121, 364, 1093...        while (h < n/3){            h = h * 3 + 1;        }        while (h >= 1) {            // 对 arr[i], arr[i-h], arr[i-2*h], arr[i-3*h]... 使用插入排序            for (int i = h; i < n; i++) {                Integer temp = arr[i];                int j = i;                for (; j >= h; j = j - h) {                    if (arr[j - h].compareTo(temp) > 0) {                        arr[j] = arr[j - h];                    } else {                        break;                    }                }                arr[j] = temp;            }            h /= 3;        }    }    // 单元测试    public static void main(String[] args) {        int N = 20000;        Integer[] arr = SortTestHelper.generateRandomArray(N, 0, 100000);        System.out.println("排序前的数组为：");        SortTestHelper.printArray(arr);        Long start = System.currentTimeMillis();        ShellSort.sort(arr);        Long end = System.currentTimeMillis();        System.out.println("-------------------------------------------");        System.out.println("排序后的数组为：");        SortTestHelper.printArray(arr);        System.out.println("-------------------------------------------");        System.out.println("排序后的数组是否有序：");        if (SortTestHelper.isSorted(arr)){            System.out.println("数组有序~");        } else {            System.out.println("数组无序！");        }        System.out.println("-------------------------------------------");        System.out.println( "排序算法的运行时间为"+ " : " + (end-start) + "ms" );    }}