Cod sursa(job #2559795)

Utilizator georgeoctavianGeorge Octavian Grumazescu georgeoctavian Data 27 februarie 2020 16:50:18
Problema Invers modular Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 0.78 kb
#include <bits/stdc++.h>
#define st first
#define nd second
#define pb push_back
#define N 50005
using namespace std;
ifstream fin("inversmodular.in");
ofstream fout("inversmodular.out");
typedef long long ll;
ll a,n;
ll phi(ll nr)
{
    ll ans=nr;
    for(int d=2;d*d<=nr;d++)
    {
        if(nr%d==0)
        {
            while(nr%d==0)
                nr/=d;
            ans-=ans/d;
        }
    }
    if(nr>1)ans-=ans/nr;
    return ans-1;
}
ll exp(ll a, ll p)
{
    ll rez=1;
    while(p)
    {
        if(p%2==0)
        {
            a=(a*a)%n;
            p/=2;
        }
        else
        {
            rez=(rez*a)%n;
            p--;
        }
    }
    return rez;
}
int main()
{
    fin>>a>>n;
    fout<<exp(a,phi(n));
    return 0;
}