Merge pull request neetcode-gh#1301 from voski/patch-11

Create 0002-Add-Two-Numbers.rb

Author: Ahmad-A0

ruby/2-Add-Two-Numbers.rb

@@ -0,0 +1,33 @@
+# Definition for singly-linked list.
+# class ListNode
+#     attr_accessor :val, :next
+#     def initialize(val = 0, _next = nil)
+#         @val = val
+#         @next = _next
+#     end
+# end
+# @param {ListNode} l1
+# @param {ListNode} l2
+# @return {ListNode}
+def add_two_numbers(l1, l2)
+    dummy_head = ListNode.new()
+    curr = dummy_head
+    
+    carry = 0
+    while l1 || l2 || carry > 0
+        l1_val = l1 ? l1.val : 0
+        l2_val = l2 ? l2.val : 0
+        
+        sum = l1_val + l2_val + carry
+        ones = sum % 10
+        carry = sum / 10
+
+        curr.next = ListNode.new(ones)
+        
+        curr = curr.next
+        l1 = l1.next if l1
+        l2 = l2.next if l2
+    end
+
+    dummy_head.next
+end