下面函数可以将 n 的所有质因数找出来，其时间复杂度是（    ）。

#include <iostream>

#include <vector>

vector<int> get_prime_factors(int n) {

      vector<int> factors;

      while (n % 2 == 0) {

            factors.push_back(2);

            n /= 2;

      }

      for (int i = 3; i * i <= n; i += 2) {

            while (n % i == 0) {

                  factors.push_back(i);

                  n /= i;

            }

      }

      if (n > 2) {

            factors.push_back(n);

      }

      return factors;

}