Cod sursa(job #2365981)

Utilizator stefanst77Luca Stefan Ioan stefanst77 Data 4 martie 2019 17:49:28
Problema Invers modular Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 0.9 kb
#include <bits/stdc++.h>

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

int A, N;

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

    return fi;
}

int PutLog(int a, int n, int modulo)
{
    long long rez = 1;
    while (n != 0)
    {
        if (n % 2 == 1)
            rez = (1LL * rez * a) % modulo;
        n /= 2;
        a = (1LL * a * a) % modulo;
    }
    return rez;
}

int main()
{
    int fi, prod;
    fin >> A >> N;

    fi = Fi(N) - 1;

    prod = PutLog(A, fi, N);

    fout << prod << "\n";
    fin.close();
    fout.close();
    return 0;
}