快速排序

#include <stdio.h>

int partition(int A[], int p, int q) {
int x = A[p];
int i = p;
int j;
for (j=p+1; j<=q; j++) {
if (A[j]<=x) {
i++;
int temp = A[i];
A[i] = A[j];
A[j] = temp;
}
}
int temp = A[p];
A[p] = A[i];
A[i] = temp;
return i;
}

void quickSort(int A[], int L, int R) {
if (L <= R) {
int mid = partition(A, L, R);
quickSort(A, L, mid-1);
quickSort(A, mid+1, R);
}
}

int main() {
int A[5] = {3, 6, 8, 2, 1};
quickSort(A, 0, 4);
int i;
for (i=0; i<5; i++) {
printf("%d ", A[i]);
}
return 0;
}

　　

*************************************************************************************8

#include <stdio.h>
int quick_sort(int a[], int low, int high)//一趟排序找出并确定枢轴位置
{
int key = 0;
a[0]= a[low];
key = a[low];
while (low < high)
{
while (low < high && a[high] >= key) high--;
a[low] = a[high];
while (low < high && a[low] <= key) low++;
a[high] = a[low];
}
a[low] = a[0];
return low;
}
void qsort(int a[], int low, int high)//递归进行排序，每次确定每部分的枢轴未知直到该部分只剩下一个元素为止
{
int key = 0;
if (low < high)
{
key = quick_sort(a, low, high);
qsort(a, low, key-1);
qsort(a, key+1, high);
}
}
void Quicksort(int a[])
{
qsort(a,1,7);
}

int main()
{
int a[8] = {0, 23, 27, 45, 98, 65, 17, 78};
int i = 0;
for (i = 1; i < 8; i++) //排序前

printf("%4d", a[i]);

printf(" ");
Quicksort(a);//调用排序函数
for (i = 1; i < 8; i++) //排序后

printf("%4d", a[i]);

printf(" ");
}

***********************************************************************************

#include <stdio.h>
int quick_sort(int a[], int low, int high)//一趟排序找出并确定枢轴位置
{
int key = 0;
a[0]= a[low];
key = a[low];
while (low < high)
{
while (low < high && a[high] >= key) high--;
a[low] = a[high];
while (low < high && a[low] <= key) low++;
a[high] = a[low];
}
a[low] = a[0];
return low;
}
void qsort(int a[], int low, int high)//递归进行排序，每次确定每部分的枢轴未知直到该部分只剩下一个元素为止
{
int key = 0;
if (low < high)
{
key = quick_sort(a, low, high);
qsort(a, low, key-1);
qsort(a, key+1, high);
}
}
void Quicksort(int a[])
{
qsort(a,1,7);
}

int main()
{
int a[8] = {0, 23, 27, 45, 98, 65, 17, 78};
int i = 0;
for (i = 1; i < 8; i++) //排序前
{
printf("%4d", a[i]);
}
printf(" ");
Quicksort(a);//调用排序函数
for (i = 1; i < 8; i++) //排序后
{
printf("%4d", a[i]);
}
printf(" ");
}

　　

*****************************

//请问qsort排序怎么写啊？

#include <stdio.h>
#include<stdlib.h>
int comp(const void *a,const void *b)
{
return *(int *)a-*(int *)b;
}
int main()
{
int i,n,a[20];

scanf("%d",&n);
for(i=0;i<n;i++)
scanf("%d",&a[i]);
qsort(a,n,sizeof(int),comp);
for(i=0;i<n;i++)
printf("%d ",a[i]);
return 0;

}