Cod sursa(job #2456319)

Utilizator NopeCarp Rafael Nope Data 14 septembrie 2019 10:31:39
Problema Invers modular Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 0.74 kb
#include <fstream>
using namespace std;

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

int Phi(int n)
{
    int sol = n , p;
    for (p = 2 ; n > 1 && p * p <= n ; p++)
        if (n % p == 0)
        {
            sol = sol / p * (p - 1);
            while (n % p == 0)
                    n /= p;
        }
    if (n > 1) sol = sol / n * (n - 1);
    return sol;
}

int lg(int a , int b , int mod)
{
    int p = 1;
    while (b > 0)
    {
        if (b % 2 == 1)
            p = 1LL * p * a % mod;
        b /= 2;
        a = 1LL * a * a % mod;
    }
    return p;
}

int main()
{
    int a , n , rez;
    fin >> a >> n;
    rez = lg(a , Phi(n) - 1 , n);
    fout << rez;
    return 0;
}