Cod sursa(job #2173175)

Utilizator andreigeorge08Sandu Ciorba andreigeorge08 Data 15 martie 2018 21:01:13
Problema Invers modular Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.8 kb
#include <bits/stdc++.h>

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

int n, a;

long long Fi(int n)
{
    int fi = n;

    for(int di = 2; di * di <= n && n > 1; di++)
        if(n % di == 0)
        {
            fi = (fi / di) * (di - 1);
            while(n % di == 0) n /= di;
        }
    if(n > 1) fi = (fi / n) * (n - 1);
    return fi;
}

long long lgput(long long x, long long y)
{
    long long prod = 1;
    while(y)
    {
        if(y % 2) prod = (1LL * prod * x) % n;
        y /= 2;
        x = (1ll * x * x) % n;
    }
    return prod;
}

void Citire()
{
    /// a ^ (fi - 1)

    fin >> a >> n;

    long long fi = Fi(n) - 1;

    fout << lgput(a, fi) << "\n";
}
int main()
{
    Citire();
    return 0;
}