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\n", 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("\n");
    Quicksort(a);//调用排序函数
    for (i = 1; i < 8; i++) //排序后
    
        printf("%4d", a[i]);
    
    printf("\n");
}




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




#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("\n\n");
    Quicksort(a);//调用排序函数
    for (i = 1; i < 8; i++) //排序后
    {
        printf("%4d", a[i]);
    }
    printf("\n\n");
}

　　

 

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

 

//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\n",a[i]);
    return 0;

}