poj 2407 Relatives（欧拉函数模板）

Relatives

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 12496		Accepted: 6087

Description

Given n, a positive integer, how many positive integers less than n are relatively prime to n? Two integers a and b are relatively prime if there are no integers x > 1, y > 0, z > 0 such that a = xy and b = xz.

Input

There are several test cases. For each test case, standard input contains a line with n <= 1,000,000,000. A line containing 0 follows the last case.

Output

For each test case there should be single line of output answering the question posed above.

Sample Input

7
12
0

Sample Output

6
4
#include<stdio.h>
#include<string.h>
int n,i;
int oular(int n)//欧拉函数模板得出的是小于n的与n互质（就是二个数的最大公约数是1）的个数 
{
	int res=n;
	int a=n;
	for(i=2;i*i<=a;i++)
	{
		if(a%i==0)
		{
			res=res/i*(i-1);
			while(a%i==0)
			a=a/i;
		}
	}
	if(a>1)
	res=res/a*(a-1);
	return res;
}
int main()
{
	int n;
	while(~scanf("%d",&n),n)
	{
		printf("%d\n",oular(n));
	} 
	return 0;
}