快速排序的思考

1）快速排序的基本思想：

      设当前待排序的无序区为R[low......high]，在R[low......high]中任选一个记录作为基准(Pivot)，以此基准将当前无序区划分为左、右两个较小的子区间R[low..pivotpos-1)和R[pivotpos+1..high]，并使左边子区间中所有记录的关键字均不大于基准，右边的子区间中所有记录的关键字均不小于基准。基准记录不参与下次排序，它已经处于排好位pivotpos。下次递归调用快速排序对左、右子区间R[low..pivotpos-1]和R[pivotpos+1..high]快速排序。

 2）具体代码：

     [code]

     package com.amplesky;

    public class QuickSort
   {

          public static void main(String[] args)
         {
                int [] a = {5,6,7,65,3,4,2,6,4,5};
                int low = 0;
                int heigh = a.length -1;
               quickSort(a,low,heigh);
               for (int i =0; i <= heigh ;i++)
               {
                     System.out.print(a[i]+"   "); 
               }
                System.out.println();

           }

 

           public static void quickSort(int a[], int low,int heigh)
          {
                 if( low >= heigh)
                {
                         return ;
                }
                int index = partion(a, low, heigh);
                quickSort(a,low, index -1);
                quickSort(a,index+1, heigh);
          }
 
        public static int partion(int a[], int low,int heigh)
       {
              int swap = a[low];
             while(low < heigh)
            {
                    while(low < heigh && a[heigh] >= swap)
                  {  
                          heigh -- ;
                  }
                   if(low < heigh)
                  {
                          a[low++] = a[heigh];
                  }
                  while(low < heigh && a[low] <= swap)
                  {
                          low ++ ;
                  }
                  if(low < heigh)
                  {
                         a[heigh--] = a[low];
                  }
         }
          a[low]= swap;
           return low;
      }
}
[/code]