def sum1to(n):
    """
    choose2(int) -> int
    
    Return the number of subsets of length 2 that can be formed from a set
    of size n, or alternatively: sum the numbers from 1 to n, inclusive.
    """
    n = int(n)+1
    return int((n * (n-1)) / 2)

def linear_solution(n):
    """Sum of multiples of 3 or 5 that are less than 1000 in O(n) expected
    time."""
    s = 0
    for i in range(1, n):
        if (i % 3) == 0 or (i % 5) == 0:
            s = s + i
    return s

def constant_solution(n):
    """Sum of multiples of 3 or 5 that are less than 1000 in O(1) expected
    time."""
    n = int(n) - 1
    return int(3 * sum1to(n/3)) + int(5 * sum1to(n/5)) - int(15 * sum1to(n/15))

print linear_solution(1000), constant_solution(1000)

233168 233168