Cod sursa(job #2281398)

Utilizator borzaalexAlexandru Borza borzaalex Data 12 noiembrie 2018 10:32:44
Problema Invers modular Scor 10
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 0.73 kb
#include <bits/stdc++.h>
using namespace std;
long long a,n,phideN;

    ifstream fin("inversmodular.in");
    ofstream fout("inversmodular.out");
long long int putere(int a, int p)
{
    if(p==0) return 1;
    else if(p%2==0)
    {
        long long int x=putere(a,p/2);
        return x*x;
    }
    else if(p%2==1)
        return a*putere(a,p-1);

}

int main()
{
    fin>>a>>n;
    phideN=1;
    long long int d=2;
    long long int m=n;
    while(m>1)
    {
        if(d*d>m) d=m;

        if(m%d==0)
        {
           while(m%d==0) m/=d,phideN*=d;

           phideN=phideN/d*(d-1);
        }
        if(d==2) d=3;
        else d+=2;

    }


    fout<<putere(a,phideN-1)%n;
    return 0;

}