Problem 7

By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13.

What is the 10 001st prime number?

#!/usr/bin/ruby
# My implementation of Sieve of Eratosthenes algoritm
factor = [2]
n = 3
while factor.size < 10001
	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)
	end
	n += 1
end
puts factor[factor.size-1]