计时器比较 gcd与stein

#include<iostream>
#include<cstdio>
#include<math.h>
#include<ctime>

using namespace std;

__int64 gcd(__int64 a,__int64 b){return b ? gcd(b,a%b): a;}

__int64 stein(__int64 a,__int64 b)
{
	if(a==b)return a;
	if(a==0)return b;
	if(b==0)return a;

	if(a<b)swap(a,b);
printf("%I64d  %I64d\n",a,b);
	int r=0;
	while(b>0)//b 小的
	{
		if(a%2==0 && b%2==0)
		{
			a=a>>1;
			b=b>>1;
			r++;
		}
		else if( a%2==0 && b%2!=0)	a=a>>1;
		else if(a%2!=0 && b%2==0 ) b=b>>1;
		else a=(a-b)>>1;
		if(a<b)swap(a,b);
	}
	return a<<r;
}

int main()
{
	__int64 first,secend;
	while(scanf("%I64d%I64d",&first,&secend)!=EOF)
	{
		clock_t start,finish;
		int time1,time2;

		__int64 ans;
		start=clock();
		ans=gcd(first,secend);
		finish=clock();
		time1= (finish=start)/1000;
		printf("gcd用时:%d MS\n最大公约数: %I64d\n\n",time1,ans);

		start=clock();
		ans=stein(first,secend);
		finish=clock();
		time2= (finish=start)/1000;

		printf("stein用时:%d MS\n最大公约数: %I64d\n",time2,ans);
	}
	return 0;
}


/*

*/