Cod sursa(job #3216187)

Utilizator Alex_DumitrascuAlex Dumitrascu Alex_Dumitrascu Data 15 martie 2024 18:21:55
Problema Invers modular Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 0.79 kb
#include <bits/stdc++.h>
#define ll long long
using namespace std;

ifstream fin ("inversmodular.in");
ofstream fout ("inversmodular.out");
int mod;
int phi(int n)
{
    int r = n , d = 2;
    while(n > 1)
    {
        if(n % d == 0)
        {
            r = r / d * (d - 1);
            while(n % d == 0)
                n /= d;
        }
        d ++;
        if(d * d > n)
            d = n;
    }
    return r;
}

ll exponentiere (ll a, ll b)
{
    ll rez=1;
    while (b!=0) {
        if (b%2==1) {
            rez*=a;
            rez%=mod;
        }
        a*=a;
        a%=mod;
        b/=2;
    }
    return rez;
}

int main()
{
    int n;
    fin>>n>>mod;
    int ph=phi(mod);
    int rez=exponentiere(n, ph-1);
    fout<<rez;
    return 0;
}