【POJ 2407】 Relatives

【题目链接】

           点击打开链接

【算法】

          欧拉函数

【代码】

          

#include <algorithm>
#include <bitset>
#include <cctype>
#include <cerrno>
#include <clocale>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <limits>
#include <list>
#include <map>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <utility>
#include <vector>
#include <cwchar>
#include <cwctype>
#include <stack>
#include <limits.h>
using namespace std;
typedef long long ll;

ll n;

template <typename T> inline void read(T &x) {
        ll f = 1; x = 0;
        char c = getchar();
        for (; !isdigit(c); c = getchar()) { if (c == '-') f = -f; }
        for (; isdigit(c); c = getchar()) x = (x << 3) + (x << 1) + c - '0';
        x *= f;
}
template <typename T> inline void write(T x) {
        if (x < 0) { x = -x; putchar('-'); }
        if (x > 9) write(x/10);
        putchar(x%10+'0');    
}
template <typename T> inline void writeln(T x) {
        write(x);
        puts("");    
}

inline int phi(ll n) {
        ll i,ret=n;
        for (i = 2; i <= n; i++) {
                if (n % i == 0) {
                        while (n % i == 0) n /= i;
                        ret = ret * (i - 1) / i;
                }
        }    
        if (n > 1) ret = ret * (n - 1) / n;
        return ret;
}

int main() {
    
    while (true) {
            read(n);
            if (!n) return 0;
            writeln(phi(n));    
    }
    
    return 0;
}