Cod sursa(job #2539773)

Utilizator handicapatucavasi eduard handicapatu Data 6 februarie 2020 12:00:20
Problema Invers modular Scor 10
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 0.75 kb
#include <iostream>
#include<fstream>
#include<math.h>
using namespace std;
int a, n;
long long int exponentiererapida(int a,int w){
    long long int p=1;
    while(w>0){
        if(w%2==0){
            a=(a*a)%n;
            w=w/2;
        }
        else{
            p=(p*a)%n;
            w=w-1;
        }
    }
    return p%n;
}
long long phi(long long x)
{ long long  p=1;
  for(long long i=2;i*i<=x;i++)
  { if(x%i!=0)
       continue;
    long long  e=0,k=1;
    while(x%i==0)
        x/=i,e++,k*=i;
    k/=i;
    p=(i-1)*k;
  }
  if(x!=1)
     p*=(x-1);
  return p;
}
int main()
{
    ifstream f("inversmodular.in");
    ofstream g("inversmodular.out");
    f>>a>>n;
    g<<exponentiererapida(a,phi(n)-1);
    return 0;
}