快速排序的思想在程序中经常用到，虽然C++给出了快速排序的函数调用，但是很多程序可能需要自己写排序过程，快速排序就会被用到，以下是快速排序算法：
快速排序时间复杂度是O（nlog(n)），在数据有序的情况下最耗时
（程序输入如果使用scanf_s则编译器为vs2013）
#include<stdio.h>
#include<stdlib.h>
#define MAXSIZE 1<<9
typedef struct {
int key;
}RedType;
typedef struct {
RedType elemword[MAXSIZE];
int count;
}SqList;
void InitialSqList(SqList &);
void QuickSort(SqList &);
void QSort(SqList &, int, int);
int Partition(SqList &, int, int);
void PrintSqList(SqList);
void InitialSqList(SqList &L)
{
int i;
scanf("%d", &L.count);
for (i = 1; i <= L.count; i++)
scanf("%d", &L.elemword[i].key);
}
void PrintSqList(SqList L)
{
int i;
for (i = 1; i <= L.count; i++)
printf("%d", L.elemword[i].key);
printf("\n");
}
void QSort(SqList &L, int low, int high)
{
int pivotloc;
if (low<high)
{
pivotloc = Partition(L, low, high);
QSort(L, low, pivotloc - 1);
QSort(L, pivotloc + 1, high);
}
}
void QuickSort(SqList &L)
{
QSort(L, 1, L.count);
}
int Partition(SqList &L, int low, int high)
{
int pivotkey;
pivotkey = L.elemword[low].key;
while (low<high)
{
while (low<high&&L.elemword[high].key >= pivotkey)
--high;
L.elemword[low].key = L.elemword[high].key;
while (low<high&&L.elemword[low].key <= pivotkey)
++low;
L.elemword[high].key = L.elemword[low].key;
}
L.elemword[low].key = pivotkey;
return low;
}
int main()
{
SqList L;
int i;
while (scanf("%d",&L.count)!=EOF)
{
L.count = L.count + 1;
for (i = 1; i <= L.count; i++)
scanf("%d", &L.elemword[i].key);
QuickSort(L);
PrintSqList(L);
}
return 0;
}
