POJ 2407 Relatives (欧拉函数)

Relatives
Time Limit: 1000MS
Memory Limit: 65536K
Total Submissions: 11352
Accepted: 5531

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

Source

Waterloo local 2002.07.01
 
题目链接:http://poj.org/problem?id=2407

题目大意:输入一个n求euler[n]

题目分析:裸的欧拉函数

#include <cstdio>
#include <cmath>
int main()
{
    int n, ans;
    while(scanf("%d", &n) != EOF && n)
    {
        ans = n;
        for(int i = 2; i <= sqrt(n); i++)
            if(n % i == 0)
            {
                ans = ans - ans / i;
                while(n % i == 0)
                    n /= i;
            }
        if(n > 1)
            ans = ans - ans / n;
        printf("%d\n", ans);
    }
}


你可能感兴趣的:(数论,欧拉函数,poj)