hdu1787赤裸裸的欧拉涵数

/*
 * hdu1787/win.cpp
 * Created on: 2012-7-9
 * Author    : ben
 */
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <ctime>
#include <iostream>
#include <algorithm>
#include <queue>
#include <set>
#include <map>
#include <stack>
#include <string>
#include <vector>
#include <deque>
#include <list>
#include <functional>
#include <numeric>
#include <cctype>
using namespace std;

int getPhi(int n) {
    int i, te, phi;
    te = (int) sqrt(n * 1.0);
    for(i = 2, phi = n; i <= te; i++) {
        if(n % i == 0) {
            phi = phi / i * (i - 1);
            while(n % i == 0) {
                n /= i;
            }
        }
    }
    if(n > 1) {
        phi = phi / n * (n - 1);
    }
    return phi;
}

int main() {
#ifndef ONLINE_JUDGE
    freopen("data.in", "r", stdin);
#endif
    int N;
    while(scanf("%d", &N) == 1 && N != 0) {
        printf("%d\n", N - 1 - getPhi(N));
    }
    return 0;
}

转载于:https://www.cnblogs.com/moonbay/archive/2012/07/09/2583586.html