Problem 10

The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.

Find the sum of all the primes below two million.

#!/usr/bin/ruby
# My implementation of Sieve of Eratosthenes algoritm
factor = [2]
n = 3
sum = 2 # 1 is not a prime number
while n < 2000000
	skip = false
	limit = Math.sqrt(n).ceil
	for i in 0...factor.size
		if factor[i] > limit 
			break
		elsif  n % factor[i] == 0 
			skip = true
			break
		end
	end
	if !skip
		factor.push(n)
		sum += n
	end
	n += 1
end
puts sum