Cod sursa(job #2433976)

Utilizator blotucosmincosmin blotucosmin Data 30 iunie 2019 10:15:03
Problema Invers modular Scor 10
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 0.73 kb
#include<fstream>
using namespace std;
ifstream fin("inversmodular.in");
ofstream fout("inversmodular.out");
long long lgnp(long long n, long long p)
{
    long long r=1;
    while(p)
    {
        if(p%2==1) r=r*n;
        p/=2;
        n*=n;
    }
    return r;
}
int phi(int n)
{
    int d=2,fm;
    long long nr=1;
    do
    {
        fm=0;
        while(n%d==0)
        {
            n/=d;
            fm++;
        }
        if(fm>0) nr=nr*(d-1)*lgnp(d,fm-1);
        d++;
        if(d*d>n&&n>1)
        {
            nr=nr*(n-1);
            n=1;
        }
    }while(n>1);
    return nr;
}
using namespace std;
int a,n;
int main()
{
    fin>>a>>n;
    fout<<lgnp(a,phi(n)-1)%n;
    return 0;
}