test/phi.test.cpp

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Last update: 2025-06-11 17:30:11+09:00
Problem: https://onlinejudge.u-aizu.ac.jp/courses/library/6/NTL/1/NTL_1_D

Depends on

Euler's Phi-function (C++/math/euler_phi.hpp)

Code

#define PROBLEM "https://onlinejudge.u-aizu.ac.jp/courses/library/6/NTL/1/NTL_1_D"
#include <iostream>
#include "C++/math/euler_phi.hpp"
int main() {
    long n;
    std::cin >> n;
    std::cout << man::euler_phi(n) << '\n';
}

#line 1 "test/phi.test.cpp"
#define PROBLEM "https://onlinejudge.u-aizu.ac.jp/courses/library/6/NTL/1/NTL_1_D"
#include <iostream>
#line 2 "C++/math/euler_phi.hpp"
namespace man {
template <std::integral T> constexpr inline T euler_phi(T n) noexcept {
	T ret = n;
	for(T i = 2; i * i <= n; ++i) {
	    if(n % i == 0) {
			ret -= ret / i;
			while(n % i == 0) {
				n /= i;
			}
		}
	}
	if(n > 1) {
		ret -= ret / n;
	}
	return ret;
}
}

/**
 * @brief Euler's Phi-function
 */
#line 4 "test/phi.test.cpp"
int main() {
    long n;
    std::cin >> n;
    std::cout << man::euler_phi(n) << '\n';
}