Finding inverse

#include <iostream>
using namespace std;

// Función para calcular el GCD y los coeficientes x, y usando el Algoritmo Extendido de Euclides
int extended_gcd(int a, int b, int &x, int &y) {
    if (b == 0) {
        x = 1;
        y = 0;
        return a;
    }
    int x1, y1;
    int gcd = extended_gcd(b, a % b, x1, y1);
    x = y1;
    y = x1 - (a / b) * y1;
    return gcd;
}

// Función para encontrar el inverso modular
int modular_inverse(int a, int M) {
    int x, y;
    int gcd = extended_gcd(a, M, x, y);
    if (gcd != 1) {
        return -1; // No existe el inverso modular si gcd(a, M) != 1
    }
    x = (x % M + M) % M; // Asegurar que x esté en el rango 0 < x < M
    return x;
}

int main() {
    int a, M;
    cin >> a >> M;

    int result = modular_inverse(a, M);
    cout << result << endl;

    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED