排序（三）——快速排序,堆排序，归并排序

快速排序

#include<stdio.h>
int A[10]={7,4,1,8,5,2,9,6,3,0};
void QuickSort(int A[],int low,int high)
{
    int temp;
    int i=low,j=high;
    if(low<high)
    {
        temp=A[low];
        while(i<j)
        {
            while(j>i&&A[j]>=temp) --j;
            if(i<j)
            {
                A[i]=A[j];
                ++i;
            }
            while(i<j&&A[i]<temp) ++i;
            if(i<j)
            {
                A[j]=A[i];
                --j;
            }
        }
        A[i]=temp;
        QuickSort(A,low,i-1);
        QuickSort(A,i+1,high);
    }

}
int main()
{
    for(int i=0;i<10;i++)
    {
        printf("%d ",A[i]);
    }
    printf("\n");
    QuickSort(A,0,9);
    for(int i=0;i<10;i++)
    {
        printf("%d ",A[i]);
    }
    printf("\n");
}

堆排序：

#include<stdio.h>
void Sift(int R[],int low,int high)
{
    int i=low,j=2*i;
    int temp=R[i];
    while(j<=high)
    {
        if(j<high&&R[j]<R[j+1])
            ++j;
        if(temp<R[j])
        {
            R[i]=R[j];
            i=j;
            j=2*i;
        }
        else break;
    }
    R[i]=temp;
}
void heapSort(int R[],int n)
{
    int i;
    int temp;
    for(i=n/2;i>=0;--i)
        Sift(R,i,n);
    for(i=n;i>=1;--i)
    {
        temp=R[0];
        R[0]=R[i];
        R[i]=temp;
        Sift(R,0,i-1);
    }
}
int main()
{
    int A[20]={7,4,1,8,5,2,0,9,6,3,11,14,17,18,15,12,10,19,16,13};
    heapSort(A,19);
    for(int i=0;i<20;i++)
    {
        printf("%d ",A[i]);
    }
    printf("\n");
}

归并排序

#include<stdio.h>
#include<stdlib.h>
void merge(int *p,int low,int mid,int high)
{
	int i,k;
	int* temp = (int*)malloc((high-low+1)*sizeof(int));//合并空间
	int start1 = low;
	int end1 = mid;
	int start2 = mid+1;
	int end2 = high;
	//比较两个指针所指向的元素，选择相对小的元素放入到合并空间，并移动指针到下一位置
	for (k = 0;start1<=end1 && start2<=end2;k++)
	{
		if (p[start1]<p[start2])
			temp[k] = p[start1++];
		else
			temp[k] = p[start2++];
	}
	//检测剩余项，若有剩余，直接拷贝出来粘到合并序列尾
	while (start1<=end1)
		temp[k++] = p[start1++];
	while (start2<=end2)
		temp[k++] = p[start2++];
	//将排好序的数组拷贝到原数组
	for (i = 0;i<high-low+1;i++)
		p[low+i] = temp[i];
	//合并过程
	printf("%d:",mid);
	for (i = 0;i<high-low+1;i++)
		printf("%d ",p[low+i]);
	printf("\n");
	free(temp);
}
void merge_sort(int*p,int low,int high)
{
	int mid = (low+high)/2;
	if (low <high)
	{
		merge_sort(p,low,mid);
		merge_sort(p,mid+1,high);
		merge(p,low,mid,high);
	}
}
int main()
{
    int A[10]={7,4,1,8,5,2,0,9,6,3};
    merge_sort(A,0,9);
    for(int i=0;i<10;i++)
    {
        printf("%d ",A[i]);
    }
    printf("\n");
}