求最大公约数

//求最大公约数
//利用欧几里得算法（也叫辗转相除法）

#include "stdafx.h"

//递归程序
unsigned int GcdRecursively (unsigned int x, unsigned int y)
{
	if (x == 0 || y == 0)
		return x+y;//return非0值

	return GcdRecursively(y,x%y);
}

//循环程序
unsigned int GcdIteratively (unsigned int x, unsigned int y)
{
	if (x == 0 || y == 0)
		return 0;

	unsigned int temp = x % y;
	while (temp)
	{
		x = y;
		y = temp;
		temp = x % y;
	}
	return y;
}

int _tmain(int argc, _TCHAR* argv[])
{
	unsigned int x = 90;
	unsigned int y = 60;
	unsigned int gcd = GcdRecursively(x,y);
	gcd = GcdIteratively(x,y);
	return 0;
}

但是循环程序不够简洁，有重复的部分。这样写更好：

unsigned int GcdIteratively2 (unsigned int x, unsigned int y)
{
	if (x == 0 || y == 0)
		return 0;

	unsigned int remain = 0;
	while (y)
	{
		remain = x % y;
		x = y;
		y = remain;
	}
	return x;
}