Cod sursa(job #2135463)

Utilizator lilianaursacheLiliana Ursache lilianaursache Data 18 februarie 2018 21:01:26
Problema Invers modular Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.58 kb
#include <fstream>
using namespace std;
ifstream cin("inversmodular.in");
ofstream cout("inversmodular.out");
long long a,n,p;

long long fi(int n) {
    long long r=n;
    for (int i=2; i*i<=n; i++)
        if (n % i == 0)
        {
            while(n%i==0) n/=i;
            r-=r/i;
        }
    if (n!=1) r-=r/n;
    return r;
}

long long rid(long long a, long long b) {
    if (b==0) return 1;
    long long x=rid(a,b/2);
    if (b%2) return x*x%n*a%n;
    return x*x%n;
}

int main()
{
    cin>>a>>n;
    p=fi(n)-1;
    cout<<rid(a,p);
    return 0;
}