Cod sursa(job #2947587)

Utilizator andreipirjol5Andrei Pirjol andreipirjol5 Data 26 noiembrie 2022 13:36:53
Problema Invers modular Scor 0
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 0.96 kb
#include <iostream>

using namespace std;

FILE *fin, *fout;

const long long MOD = 1999999973;

int lgput(long base, long exp)
{
    if(exp == 1)
        return base;

    if(exp % 2 == 1)
        return (1LL * (base % MOD) * (lgput(base * base, (exp - 1) / 2) % MOD)) % MOD;

    if(exp % 2 == 0)
    {
        int half = lgput(base, exp / 2) % MOD;

        return (1LL * half * half) % MOD;
    }
}

int euler(int n)
{
  int euler = n , d = 2;

  while(d * d <= n)
  {
      if(n % d == 0)
      {
          euler = euler / d * (d - 1);

          while(n % d == 0)
            n /= d;
      }

      d++;
  }

  if(n > 1)
    euler = euler / n * (n - 1);

  return euler;
}

int main()
{
    fin = fopen("lgput.in", "r");
    fout = fopen("lgput.out", "w");

    int a , n;
    fscanf(fin , "%d%d" , &a , &n);

    fprintf(fout, "%d", lgput(a , euler(n) - 1) % n);

    fclose(fin);
    fclose(fout);
    return 0;
}