Cod sursa(job #2175186)

Utilizator GoogalAbabei Daniel Googal Data 16 martie 2018 15:50:15
Problema Invers modular Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.58 kb
#include <iostream>
#include <fstream>

using namespace std;

ifstream in("inversmodular.in");
ofstream out("inversmodular.out");

int a, n; //inv_mod al lui a fata de n

void inv_mod(long long &inv, long long &ins, int a, int b) {
  if(b == 0) {
    inv = 1;
    ins = 0;
  } else {
    inv_mod(inv, ins, b, a % b);
    swap(inv, ins);
    ins -= inv * (a / b);
  }
}

int main()
{
  in >> a >> n;

  long long inv = 0, ins;
  inv_mod(inv, ins, a, n);

  if(inv <= 0)
    inv = (inv + n) % n;
  out << inv << '\n';

  in.close();
  out.close();
  return 0;
}