#include<stdio.h>
#include<stdlib.h>
#include<time.h>
//////////////快速排序///////////////////
void quicksort(int* src,int start,int end)
{
int l=start,r=end;
int key=0;
int mid=0;
if(start>=end)
return;
///////这段代码无法得到预期的结果////////////////
#if 1
mid=(start+end)/2; printf("%d %d +++++++++>%d\n",src[mid],src[l],mid);
// key=src[mid];
src[l]=src[l]+src[mid]; printf("%d %d===",src[l],src[mid]);//会出现两个数相等情况,但不是0
src[mid]=src[l]-src[mid]; printf("%d %d\n",src[l],src[mid]);//当上面出现相等情况时,这里两个数为0
src[l]=src[l]-src[mid]; printf("%d %d %d ------->%d\n\n",src[l],key,src[mid],mid);
key=src[l];
#endif
//key=src[mid];最后可以得到正确的排序结果,key=src[l];会改变原数组中的数据。key必须初始化
#if 0
key=src[l];
src[l]=src[(start+end)/2];
src[(start+end)/2]=key;
#endif
while(l<r)
{
while((l<r)&&(key<=src[r]))
r--;
if(l<r)
src[l++]=src[r];
while((l<r)&&(key>=src[l]))
l++;
if(l<r)
src[r--]=src[l];
}
src[l]=key;
quicksort(src,start,l-1);
quicksort(src,l+1,end);
}
int main(void)
{
int* src=NULL;
int n=30;
int i=0;
clock_t start,end;
double duration;
src=(int*)malloc(n*sizeof(int));
for(i=0;i<n;i++)
src[i]=rand();
start=clock();
quicksort(src,0,n-1);
end=clock();
duration=(end-start)*1000/CLOCKS_PER_SEC;
printf("耗时%f毫秒\n\n",duration);
for(i=n-30;i<n;i++)
{
printf("%d=%d\t",i,src[i]);
if(i%6==0)
putchar('\n');
}
free(src);
return 0;
}