排序——插入排序

//Java代码（插入排序）                                                                                                                     

/*                                                                                                                                             

 * 插入排序原理：对于给定的一组记录，初始时假设第一个记录自成一个有序序列，其余记录为无序序列；   

 * 　　　　　　接着从第二个记录开始，按照记录的大小依次将当前处理的记录插入到其之前的有序序列，直到最后一个记录插入到有序序列中为止。                                           

 *                        第一个元素作为起始元素，从第二个元素开始依次插入。                                                                                                          

 */                                                                                                                                            

                                                                                                                                               

public class CharuPaixu                                                                                         

　　{                                                                                                                                              

　　public static void insertSort(int[] a) // 插入排序函数                                                                     

　　{                                                                                                                                          

　　　　if (a != null)                                                                                                                         

　　　　{                                                                                                                                      

　　　　　　for (int i=1; i<a.length; i++)                                                                                                     

　　　　{                                                                                                                                  

　　　　　　int temp = a[i]; // temp是个临时变量，存放此刻要插入的那个元素； 当i=1时，a[i]表示第2个元素                                                                 

　　　　　　int j = i; // j也是个临时变量，存数组下标                                                                                                                                                                                              

　　　　　　if (a[j-1] > temp) //当前一个元素a[j-1]大于要插入的元素

　　　　　　{                                                                                                                              

　　　　　　　　while (j>=1 && a[j-1]>temp) //当j大于等于1且元素a[j-1]还大于要插入的元素(j是一直递减的，边往前移动边与temp比较)                                              

　　　　　　{                                                                                                                          

　　　　　　　　a[j] = a[j-1];  //那么把前一个大元素往后移一位,空出它的位置(j-1)                                                                            

　　　　　　　　j--;  //j减1，此时的a[j]就是空出来的位置      

　　　　　　}                                                                                                                          

　　　　}                                                                                                                              

　　　　a[j] = temp; //最后把要插入的那个元素放到它应该在的位置。(如果前面if代码块执行了，这个位置就是前面空出来的位置)                                                              

　　　　}                                                                                                                                  

　　}                                                                                                                                      

}                                                                                                                                          

                                                                                                                                               

public static void main(String[] args)                                                                                                     

{                                                                                                                                          

　　int[] array = { 7, 3, 19, 40, 4, 7, 1 };                                                                                               

　　insertSort(array); // 调用插入排序函数 

　　for (int i = 0; i < array.length; i++) // 输出排序后的数组                                                                              

　　System.out.print(array[i] + " ");                                                                                  

　　}                                                                                                                                          

}