插入排序

插入排序的效率：O(N*N), 比较N*N/4，复制N*N/4，插入排序在随机数的情况下，比冒泡快一倍，比选择稍快，在基本有序的数组中，插入排序几乎只需要O(N)，在逆序的情况下，并不比冒泡快。

代码：

 1 package sorts;

 2 

 3 public class InsertionSort {

 4     /**

 5      * @param a the array

 6      * @param low the lower bound (inclusive)

 7      * @param high the upper bound (exclusive)

 8      * */

 9     public static <T extends Comparable<T>> void sort(T[] a, int low, int high) {

10         --high;

11         for (int i = low+1; i <= high; i++) { // index from  the second character in a

12             T cur = a[i]; // the current character to  be inserted

13             int j = i - 1; // start comparing with cell left of i

14             while ((j>=low) && (a[j].compareTo(cur) > 0)) { // while a[j]  is  out of order with cur

15                 a[j+1] = a[j];

16                 j = j - 1;

17             }

18             a[j+1] = cur;

19         }

20     }

21 }