hello.rb

# https://projecteuler.net/problem=3

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

# What is the largest prime factor of the number 600851475143 ?
sleep(5)

$factor_this = 600851475143.0
$primes = [2, 3]
$solution = [0]

def add_to_primes
  succeed = false
  target = $primes.last
  begin
    target += 1
    $primes.each do |x|
      break if (target % x) == 0.0
      succeed = true if x == $primes.last
    end
  end until (succeed)
  # puts "pushing #{target}"
  $primes.push(target)
end

# Calculate all the primes we'll need
(0..9999).each do |x|
  add_to_primes
end

# Find the primes that factor cleanly
$primes.each do |x|
  puts "Trying #{x}"
  if ($factor_this % x == 0.0)
    $factor_this = $factor_this / x
    puts "#{$factor_this * x} / #{x}"
    $solution.push(x)
    if $solution.include? $factor_this
      break
    else
      redo
    end
  end
end


puts "The solution is #{$solution}"