Cod sursa(job #2469616)

Utilizator vladadAndries Vlad Andrei vladad Data 7 octombrie 2019 19:34:54
Problema Invers modular Scor 100
Compilator cpp-64 Status done
Runda basic_stuff Marime 0.67 kb

#include <bits/stdc++.h>
using namespace std;
ifstream f("inversmodular.in");
ofstream g("inversmodular.out");
int phi(int n)
{
    int sol = n, p;
    for(p = 2; p * p <= n && n > 1; 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 lgput(int a, int n, int mod)
{
    int p = 1;
    while(n)
    {
        if(n % 2 == 1) p = 1LL * p * a % mod;
        n /= 2;
        a = 1LL * a * a % mod;
    }
    return p;
}

int main()
{
    int a, n;
    f >> a >> n;
    g << (lgput(a, (phi(n) - 1), n));
    return 0;
}