add_reversed_linked_list_digits.rb

# Add two numbers represented by linked lists

# Input:
#   First List: 7->5->9->4->6  // represents number 64957
#   Second List: 8->4 //  represents number 48
# Output
#   Resultant list: 5->0->0->5->6  // represents number 65005

def add_reversed_digits(list1, list2)
  return false unless list1 && list2
  current1 = list1.head
  current2 = list2.head
  stack1   = []
  stack2   = []

  while current1.next
    stack1 << current1.value.to_i
    current1 = current1.next
  end
  stack1 << current1.value.to_i

  while current2.next
    stack2 << current2.value.to_i
    current2 = current2.next
  end
  stack2 << current2.value.to_i

  stack1 = stack1.reverse.join.to_i
  stack2 = stack2.reverse.join.to_i
  stack1 + stack2
end