from typing import List


def get_primes(n: int) -> List[int]:
    """Return a list of all prime numbers less than n.
    
    This function determines if each integer is prime with efficiency
    O(sqrt(n)).  Memory consumption for each prime is O(1).
    
    Arguments:
        n: int
            Maximum number for the prime search

    Returns:
        List[int]: list of prime numbers
    """
    prime_list = []
    for i in range(2, n):
        is_prime = True
        for j in range(2, round(i ** (1 / 2)) + 1):
            if i % j == 0:
                is_prime = False
        if is_prime:
            prime_list.append(i)
    return prime_list