排序的八种算法

直接排序

解析：将第n位与第（n-1）位进行比较，若小则前移一位，而后继续将（n-1）与（n-2）比较，如此反复

public class direct { // private static int a[] = { 3, 2, 9, 5, 6, 1, 7, 8 }; private static int a[] = { 9, 8, 7, 6, 5, 4, 3, 2, 1 }; static int count; private static void insertSort() { for (int i = 1; i < a.length; i++) { for (int j = i - 1; j >= 0; j--) { if (a[j + 1] < a[j]) { int temp = a[j + 1]; a[j + 1] = a[j]; a[j] = temp; count++; } else { break; } } } for (int i = 0; i < a.length; i++) { System.out.print(a[i]); System.out.print("-"); } System.out.println(""); System.out.print("count:" + count); } public static void main(String[] args) { insertSort(); } }

运行结果

1-2-3-4-5-6-7-8-9- count:36

希尔排序

解析：基本思想：算法先将要排序的一组数按某个增量d（n/2,n为要排序数的个数）分成若干组，每组中记录的下标相差d.对每组中全部元素进行直接插入排序，然后再用一个较小的增量（d/2）对它进行分组，在每组中再进行直接插入排序。当增量减到1时，进行直接插入排序后，排序完成。

public class Hill { // private static int a[] = { 3, 2, 9, 5, 6, 1, 7, 8 }; private static int a[] = { 9, 8, 7, 6, 5, 4, 3, 2, 1 }; static int count; private static void HillSort() { double d1 = Math.ceil(a.length / 2); while (true) { int d = (int) d1; for (int i = 0; i < d; i++) { for (int j = d + i; j < a.length; j += d) { for (int z = j; z > i; z -= d) { if (a[z - d] > a[z]) { int temp = a[z - d]; a[z - d] = a[z]; a[z] = temp; count++; } else { break; } } } } for (int i = 0; i < a.length; i++) { System.out.print(a[i]); System.out.print("-"); } System.out.println(""); if (d == 1) break; d1 = Math.ceil(d1 / 2); } for (int i = 0; i < a.length; i++) { System.out.print(a[i]); System.out.print("-"); } System.out.print("-" + count); } public static void main(String[] args) { HillSort(); } }

运行结果

1-4-3-2-5-8-7-6-9- 1-2-3-4-5-6-7-8-9- 1-2-3-4-5-6-7-8-9- 1-2-3-4-5-6-7-8-9--8

简单排序

解析：在要排序的一组数中，选出最小的一个数与第一个位置的数交换；然后在剩下的数当中再找最小的与第二个位置的数交换，如此循环到倒数第二个数和最后一个数比较为止。

public class selectSort { private static int a[] = { 9, 8, 7, 6, 5, 4, 3, 2, 1 }; static int count; private static void selectSort() { for (int i = 0; i < a.length; i++) { int minPos = i; for (int j = i + 1; j < a.length; j++) { // 取得最小数下标 if (a[j] < a[minPos]) { minPos = j; } } // 需要交换 if (minPos != i) { int temp = a[minPos]; a[minPos] = a[i]; a[i] = temp; count++; } } System.out.print("result:"); for (int i = 0; i < a.length; i++) { System.out.print(a[i]); System.out.print("-"); } System.out.println(""); System.out.print("count:" + count); } public static void main(String[] args) { selectSort(); } }

运行结果

result:1-2-3-4-5-6-7-8-9- count:4

希尔排序

解析:选择一个基准元素,通常选择第一个元素或者最后一个元素,通过一趟扫描，将待排序列分成两部分,一部分比基准元素小,一部分大于等于基准元素,此时基准元素在其排好序后的正确位置,然后再用同样的方法递归地排序划分的两部分。

public class MyClass { static int a[] ={49, 38, 65, 97, 76, 13, 27, 49, 78, 34, 12, 64, 5, 4, 62, 99, 98, 54, 56, 17, 18, 23, 34, 15, 35, 25, 53, 51}; public static int aaa(int[] list, int low, int high) { int temp = list[low]; while (low < high) { while (low < high && temp <= list[high]) { high--; } list[low] = list[high]; while (low < high && temp >= list[low]) { low++; } list[high] = list[low]; } list[low] = temp; return low; } public static void quickSort(int[] list, int low, int high) { if (low < high) { int mid = aaa(list, low, high); quickSort(list, low, mid - 1); quickSort(list, mid + 1, high); } } public static void main(String[] args) { quickSort(a, 0, a.length - 1); for (int i = 0; i < a.length; i++) { System.out.print(a[i]); System.out.print("-"); } } }

运行结果

4-5-12-13-15-17-18-23-25-27-34-34-35-38-49-49-51-53-54-56-62-64-65-76-78-97-98-99-

归并排序

解析：归并（Merge）排序法是将两个（或两个以上）有序表合并成一个新的有序表，即把待排序序列分为若干个子序列，每个子序列是有序的。然后再把有序子序列合并为整体有序序列。

public class Merge { static int a[] = {49, 38, 65, 97, 76, 13, 27, 49, 78, 34, 12, 64, 5, 4, 62, 99, 98, 54, 56, 17, 18, 23, 34, 15, 35, 25, 53, 51}; public static void merge(int[] list, int left, int right, int mid) { //创建辅助数组，将排好的序列放在里面 int copy[] = new int[list.length]; int CLeft = left; int Orign = left; int CRight = right; int CMid = mid + 1; //最小将分为一个为一组 //每一组的第一个一定为每组最小 //将两组最小的全部移到左边一组 //左边组的组建 while (CLeft <= mid && CMid <= right) { if (list[CLeft] <= list[CMid]) { copy[Orign++] = list[CLeft++]; } else { copy[Orign++] = list[CMid++]; } } //右边边组的组建 while (CLeft <= mid) { copy[Orign++] = list[CLeft++]; } while (CMid <= right) { copy[Orign++] = list[CMid++]; } //copy到原集合 for (int i = left; i <= right; i++) { list[i] = copy[i]; } } public static void quickSort(int[] list, int left, int right) { if (left < right) { int mid = (left + right) / 2; quickSort(list, left, mid); quickSort(list, mid + 1, right); merge(list, left, right, mid); } } public static void main(String[] args) { quickSort(a, 0, a.length - 1); for (int i = 0; i < a.length; i++) { System.out.print(a[i]); System.out.print("-"); } } }

运行结果

4-5-12-13-15-17-18-23-25-27-34-34-35-38-49-49-51-53-54-56-62-64-65-76-78-97-98-99-