测评选择排序和归并排序算法的运行效率

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
#include<windows.h>
#define MAX 65536*2

//选择排序
void SelectSort(int r[],int length)
{
 int i,j,k;
 int n;
 int x;
    n=length;
 for (i=1;i<=n-1;++i)
 {
 k=i;
 for(j=i+1;j<=n;++j)
 if(r[j]<r[k])
 k=j;
 if( k!=i)
 {
 x= r[i];
 r[i]=r[k];
 r[k]=x;
 }
 }
 
}       
 
//归并排序
void merge(int a[],int tmparray[],int lpos,int rpos,int rightend)
{
 int i,leftend,numelements,tmppos;
 leftend=rpos-1;
 tmppos=lpos;
 numelements=rightend-lpos+1;
 while(lpos<=leftend && rpos<=rightend)
 if(a[lpos]<=a[rpos])
 tmparray[tmppos++]=a[lpos++];
 else
 tmparray[tmppos++]=a[rpos++];
 while(lpos<=leftend)
 tmparray[tmppos++]=a[lpos++];
 while(rpos<=rightend)
 tmparray[tmppos++]=a[rpos++];
 for(i=0;i<numelements;i++,rightend--)
 a[rightend]=tmparray[rightend];
}
void msort(int a[],int tmparray[],int left,int right)
{
 int center;
 if(left<right)
 {
 center=(left+right)/2;
 msort(a,tmparray,left,center);
 msort(a,tmparray,center+1,right);
 merge(a,tmparray,left,center+1,right);
 }
}
void mergesort(int a[],int n)
{
 int *tmparray;
 tmparray=(int*)malloc(n*sizeof(int));
 if(tmparray!=NULL)
 {
 msort(a,tmparray,0,n-1);
 free(tmparray);
 }
 else
 printf("no space for tmp array!");
} 
 
int main()
{
 long dwStart,dwStop,runtime;
 int num[MAX],a[MAX],i,j;
 dwStart=GetTickCount();
 srand((unsigned)time(NULL));
 for(i=0;i<MAX;i++)
 num[i]=rand(); 
 dwStop=GetTickCount();
 runtime=dwStop-dwStart;
 printf("生成%d个随机数运行了%ldms\n\n",MAX,runtime);
 
 printf("**************************\n");
 
 for(i=0;i<MAX;i++)
 a[i]=num[i];
 dwStart=GetTickCount();
 SelectSort(a,MAX);
 dwStop=GetTickCount();
 runtime=dwStop-dwStart;
 printf("使用简单选择排序运行了%ldms\n",runtime);
 
 
 for(i=0;i<MAX;i++)
 a[i]=num[i];
 dwStart=GetTickCount();
 mergesort(a,MAX);
 dwStop=GetTickCount();
 runtime=dwStop-dwStart;
 printf("使用归并排序运行了%ldms\n",runtime);

 printf("**************************\n");
 printf("\n排序测试完成！");
 getchar();
}