Cod sursa(job #2177606)

Utilizator IulianOleniucIulian Oleniuc IulianOleniuc Data 18 martie 2018 18:24:20
Problema Suma divizorilor Scor 30
Compilator cpp Status done
Runda Arhiva de probleme Marime 1.16 kb
#include <vector>
#include <fstream>

#define MOD 9901
#define DMAX 50000010

std::ifstream fin("sumdiv.in");
std::ofstream fout("sumdiv.out");

int sol;
int a, b;

bool sieve[DMAX];
std::vector<int> primes;

void genPrimes() {
    for (int i = 2; i <= a; i++)
        if (!sieve[i]) {
            primes.push_back(i);
            for (int j = i * i; j <= a; j += i)
                sieve[j] = true;
        }
}

int pow(int a, int b) {
    if (!b)
        return 1;

    if (b & 1)
        return a * pow(a * a % MOD, b >> 1) % MOD;
    return pow(a * a % MOD, b >> 1) % MOD;
}

int modInv(int x) {
    return pow(x, MOD - 2);
}

int main() {
    sol = 1;
    fin >> a >> b;

    genPrimes();
    for (int d = 0; a > 1; d++) {
        int exp = 0;
        while (a % primes[d] == 0) {
            exp++;
            a /= primes[d];
        }

        if (exp) {
            int fact = (pow(primes[d], exp * b + 1) - 1) * modInv(primes[d] - 1) % MOD;
            sol = sol * fact % MOD;
        }
    }

    if (sol < 0)
        fout << sol + MOD << '\n';
    else
        fout << sol << '\n';

    fout.close();
    return 0;
}