Cod sursa(job #2368614)

Utilizator RussianSmoothCriminalRodion Raskolnikov RussianSmoothCriminal Data 5 martie 2019 16:46:11
Problema Invers modular Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.09 kb
#include <fstream>

using namespace std;

ifstream fin ("inversmodular.in");
ofstream fout ("inversmodular.out");

int n;

bool IsPrime (int x)
{
    if (x <= 1) return false;
    if (x != 2 && !(x & 1)) return false;
    for (int i = 3; i * i <= x; i += 2)
        if (x % i == 0)
            return false;
    return true;

}

int Phi (int x)
{
    int f, phi;
    if (IsPrime(x))
        return x - 1;
    phi = x;
    f = 2;
    while (f * f <= x && x > 1)
    {
        if (!(x % f))
        {
            while (!(x % f))
                x /= f;
            phi /= f;
            phi *= (f - 1);
        }
        f++;
    }
    if (x > 1)
    {
        phi /= x;
        phi *= (x - 1);
    }
    return phi;
}

int Fap (int a, int b)
{
    int p = 1;
    while (b)
    {
        if (b & 1)
            p = 1LL * p * a % n;
        b >>= 1;
        a = 1LL * a * a % n;
    }
    return p;
}

void Solve ()
{
    int a;
    fin >> a >> n;
    fout << Fap(a, Phi(n) - 1);
    fout.close();
}

int main()
{
    Solve();
    return 0;
}