Cod sursa(job #1414568)

Utilizator rares96cheseliRares Cheseli rares96cheseli Data 2 aprilie 2015 19:25:27
Problema Invers modular Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.66 kb
#include <fstream>
using namespace std;
ifstream f("inversmodular.in");
ofstream g("inversmodular.out");

int N, A;

int phi(int x)
{
    int rez=x;
    for (int i=2; i*i<=x; ++i)
        if (x%i==0)
        {
            rez=rez/i*(i-1);
            while (x%i==0)
                x/=i;
        }
    if (x!=1) rez=rez/x*(x-1);
    return rez;
}

long long lgput(long long baza, int expo, int mod)
{
    long long res=1;
    while (expo)
    {
        if (expo&1) res*=baza;
        baza*=baza; baza%=mod;
        res%=mod; expo/=2;
    }
    return res;
}

int main()
{
    f>>A>>N;
    g<<lgput(A, phi(N)-1, N)<<'\n';
    return 0;
}