quint32 pollardRho(quint32 n) {
if (n < 2) return n;
if (n == 4) return 2;
if (isPropPrime(n)) return n;
Random rnd;
quint32 a = rnd.getRange(1, n - 3),
s = rnd.getRange(0, n - 1);
quint32 g, u, v;
u = v = s;
do {
u = func(u, a, n);
v = func(func(v, a, n), a, n);
g = gcd(mod(u - v, n), n);
} while (g == 1);
if (g == n) {
return pollardRho(n);
}
return g;
}
main()
{
for (int i = 0; i < 20000; i++)
prime[i] = -1;
pollardRho(22);
}
void pollardRhoFactor(quint32 n, QList<quint32> &facs) {
if (n < 2) return;
if (isPropPrime(n)) {
facs.push_back(n);
qSort(facs.begin(), facs.end());
return;
}
int g = pollardRho(n);
if (!isPropPrime(g)) {
QList<quint32> ext;
pollardRhoFactor(g, ext);
facs.append(ext);
}
else {
facs.push_back(g);
}
pollardRhoFactor(n / g, facs);
}
void factorize(LL n) { // `需要保证 n > 1`
if (isPrime(n)) divisors.push_back(n);
else { LL d = n;
while (d >= n) d = pollardRho(n, random() % (n - 1) + 1);
factorize(n / d); factorize(d);
}}
