Cod sursa(job #1653807)

Utilizator andrew_assassin789Andrei Manea andrew_assassin789 Data 16 martie 2016 16:33:45
Problema Invers modular Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.67 kb
#include <fstream>
#define w 200000001
using namespace std;
long long n;
long long po(long long a,long long b)
{
    long long rez=1;
    while (b)
    {
        if (b%2) rez=(rez*a)%n;
        a=(a*a)%n;
        b/=2;
    }
    return rez;
}
int main()
{
    ifstream f("inversmodular.in");
    ofstream g("inversmodular.out");
    long long i,phi,a,aa;
    f>>a>>n;
    aa=a;a=phi=n;
    for (i=2;i*i<=n&&a;i++)
    {
        if (a%i==0)
        {
            while (a%i==0) a/=i;
            phi=phi/i*(i-1);
        }
    }
    if (a!=1) phi=phi/a*(a-1);
    long long x=po(aa,phi-1);
    g<<x<<'\n';
    f.close();
    g.close();
    return 0;
}