Cod sursa(job #2863228)

Utilizator QwertyDvorakQwerty Dvorak QwertyDvorak Data 6 martie 2022 14:51:55
Problema Invers modular Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 0.78 kb
#include <bits/stdc++.h>
using namespace std;

#define pb push_back
#define mp make_pair
#define dbg(x) cout << #x <<": " << x << "\n";
using ll = long long;

const string myf = "inversmodular";
ifstream fin(myf + ".in");
ofstream fout(myf + ".out");

// const  int mod = 1999999973;



int a, n;

int phi(int n) {
	int ans = n;
	for (int i = 2; n && i * i <= n; ++i)
		if (n % i == 0) {
			while (n % i == 0)
				n /= i;
			ans -= ans / i;
		}
	if (n > 1)
		ans -= ans / n;
	return ans;
}

int exp(int a, int n, int mod) {
	ll p = 1;
	while (n) {
		if (n & 1)
			p = 1LL * p * a % mod;
		a = 1LL * a * a % mod;
		n >>= 1;
	}
	return p;
}

int main() {


	fin >> a >> n;
	fout << exp(a, phi(n) - 1, n) << '\n';
	fin.close();
	fout.close();
	return 0;
}