Solution to Project Euler #3

Solution to Project Euler #3

# [08:31:21] euler
# ƒ: ruby 03_lpf.rb
# 71
# 839
# 1471
# 6857
#   0.020000   0.000000   0.020000 (  0.013420)

require 'pry'
require 'prime'
require 'benchmark'

# The prime factors of 13195 are 5, 7, 13 and 29.

# What is the largest prime factor of the number 600851475143 ?

class LPF

  def lpf(prime)

    primes = Prime.each

    factor_array = []
    prime_fac = primes.next

    while prime_fac <= prime
      if (prime % prime_fac) == 0
        factor_array << prime_fac
        prime = prime / prime_fac
      else
        prime_fac = primes.next
      end
    end

    factor_array

  end

end

l = LPF.new

puts Benchmark.measure {
   answer = l.lpf(600851475143)
  puts answer}