Greplin challenge p3

subsets.rb

def subset_sum(a)
  ret = []
  while a.length > 1 do
    n = a.pop
    find_sum_from_left(n, a).each do |arr|
      ret << (arr + [n])
    end
  end
  return ret
end

def find_sum_from_left(n, a)
  ret = []
  0.upto(a.length - 1) do |i|
    break if a[i] > n
    ret << [a[i]] if a[i] == n
    find_sum_from_left(n-a[i], a[0...i]).each do |arr|
      ret << arr + [a[i]]
    end
  end
  return ret
end