import os
import times
import future
import math
import sequtils
import strutils

proc get_primes7(n: int): seq[int] =
  ## Standard optimized sieve algorithm to get a list of prime numbers
  ## this is the function to compare your functions against!

  if n < 2:
    return @[]

  if n == 2:
    return @[2]

  var s: seq[int] = @[]

  for x in countup(3, n + 1, 2):
    s.add(x)

  # n**0.5 simpler than math.sqr(n)
  let mroot = int(pow(float(n), 0.5))
  let half = len(s)
  var i = 0
  var m = 3
  var j = 0

  while m <= mroot:
    if s[i] > 0:
      j = (m * m - 3) div 2  # int div
      s[j] = 0
      while j < half:
        s[j] = 0
        j += m
    inc(i)
    m = 2 * i + 3

  let data = lc[x | (x <- s, x > 0), int]
  return concat(@[2], data)

let start_time = getTime()
let period_time = getEnv("RUN_TIME").parseInt()

while int(getTime() - start_time) < period_time:
  let res = get_primes7(10000000)
  echo("Found $1 prime numbers." % $res.len)