快速排序

记录下来，以后找方便点

  
    

   
     #include
   
     <
   
     stdio.h
   
     >
   
     
#include
   
     <
   
     stdlib.h
   
     >
   
     
#include
   
     <
   
     time.h
   
     >
   
     

   
     #define
   
      N 100
   
     

   
     void
   
      QKSort(
   
     int
   
      r[],
   
     int
   
      low,
   
     int
   
      high)

   
     /*
   
     对记录数组r[low..high]用快速排序算法进行排序
   
     */
   
     
{ 
   
     int
   
      pos;
 
   
     if
   
     (low
   
     <
   
     high)
 {
 pos
   
     =
   
     QKPass(r,low,high);
 QKSort(r,low,pos
   
     -
   
     1
   
     );
   
     //
   
     对左部子表进行排序
   
     

   
      QKSort(r,pos
   
     +
   
     1
   
     ,high);
   
     //
   
     对右部子表进行排序
   
     

   
      }

}

   
     //
   
     一趟快速排序算法
   
     

   
     int
   
      QKPass(
   
     int
   
      r[],
   
     int
   
      left,
   
     int
   
      right)
{
 
   
     int
   
      x
   
     =
   
     r[left];
   
     //
   
     选择基准记录
   
     

   
      
   
     int
   
      low
   
     =
   
     left;
 
   
     int
   
      high
   
     =
   
     right;
 
   
     while
   
     (low
   
     <
   
     high)
 {
 
   
     while
   
     (low
   
     <
   
     high
   
     &&
   
     r[high]
   
     >
   
     x)
 high
   
     --
   
     ;
   
     //
   
     high从右到左找小于x的记录
   
     

   
      
   
     if
   
     (low
   
     <
   
     high)
 {r[low]
   
     =
   
     r[high];low
   
     ++
   
     ;}
 
   
     while
   
     (low
   
     <
   
     high
   
     &&
   
     r[low]
   
     <
   
     x)
 low
   
     ++
   
     ;
 
   
     if
   
     (low
   
     <
   
     high) {r[high]
   
     =
   
     r[low];high
   
     --
   
     ;}
 }
 r[low]
   
     =
   
     x;
 
   
     return
   
      low;
}

   
     void
   
      main()
{
 
   
     int
   
      a[N];
 
   
     int
   
      i;
 srand((unsigned)time(NULL));
 
 
   
     for
   
     (i
   
     =
   
     0
   
     ;i
   
     <
   
     N;i
   
     ++
   
     )
 a[i]
   
     =
   
     rand()
   
     %
   
     5000
   
     ;
 printf(
   
     "
   
     原始数据:\n
   
     "
   
     );
 
   
     for
   
     (i
   
     =
   
     0
   
     ;i
   
     <
   
     N;i
   
     ++
   
     )
 {
 printf(
   
     "
   
     %5d
   
     "
   
     ,a[i]);
 
   
     if
   
     ((i
   
     +
   
     1
   
     )
   
     %
   
     10
   
     ==
   
     0
   
     )
 printf(
   
     "
   
     \n
   
     "
   
     );
 }

 printf(
   
     "
   
     \n排序后的数据:\n
   
     "
   
     );
 QKSort(a,
   
     0
   
     ,N
   
     -
   
     1
   
     );
 
   
     for
   
     (i
   
     =
   
     0
   
     ;i
   
     <
   
     N;i
   
     ++
   
     )
 {
 printf(
   
     "
   
     %5d
   
     "
   
     ,a[i]);
 
   
     if
   
     ((i
   
     +
   
     1
   
     )
   
     %
   
     10
   
     ==
   
     0
   
     )
 printf(
   
     "
   
     \n
   
     "
   
     );
 }
 printf(
   
     "
   
     \n
   
     "
   
     );
}