verify/aizu_online_judge/ntl/eulers_phi_function.test.cpp

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Last update: 2024-11-09 02:03:28+09:00
Problem: https://onlinejudge.u-aizu.ac.jp/courses/library/6/NTL/1/NTL_1_D

Depends on

Code

#define PROBLEM "https://onlinejudge.u-aizu.ac.jp/courses/library/6/NTL/1/NTL_1_D"
#include "../../../src/template/template.hpp"
#include "../../../src/math/euler_phi.hpp"
int main(void) {
    ll n;
    cin >> n;
    cout << euler_phi(n) << '\n';
}

#line 1 "verify/aizu_online_judge/ntl/eulers_phi_function.test.cpp"
#define PROBLEM "https://onlinejudge.u-aizu.ac.jp/courses/library/6/NTL/1/NTL_1_D"
#line 2 "src/template/template.hpp"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<long long, long long>;
#define rep(i, a, b) for(long long i = (a); i < (b); ++i)
#define rrep(i, a, b) for(long long i = (a); i >= (b); --i)
constexpr long long inf = 4e18;
struct SetupIO {
    SetupIO() {
        ios::sync_with_stdio(0);
        cin.tie(0);
        cout << fixed << setprecision(30);
    }
} setup_io;
#line 3 "src/math/euler_phi.hpp"
constexpr long long euler_phi(long long n) {
    long long res = max(n, 0ll);
    for(long long i = 2; i * i <= n; ++i) {
        if(n % i == 0) {
            res -= res / i;
            while(n % i == 0) n /= i;
        }
    }
    if(n > 1) res -= res / n;
    return res;
}
#line 4 "verify/aizu_online_judge/ntl/eulers_phi_function.test.cpp"
int main(void) {
    ll n;
    cin >> n;
    cout << euler_phi(n) << '\n';
}