【POJ 2407】 Relatives
【题目链接】
【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; }