Question

I came across this excellent piece of code over at http://projecteuler.net/ but I’m having trouble wrapping my mind around a certain part of it.

def generate(n, factors=[])
  return factors if n == 1
  new_factor = (2..n).find {|f| n % f == 0}
  generate(n / new_factor, factors << [new_factor])
end

factors = []
generate(4356463234, factors)

Question: When the generate function calls upon itself in line 4, what does factors << [new_factor] do?

Thank you for your insight!

Answer 1

It appends [new_factor] to the end of the factors array.