Adding sum-root-to-leaf-numbers (medium, ruby).

Author: rboyd

medium/sum-root-to-leaf-numbers/sub.rb

@@ -0,0 +1,34 @@
+# Definition for a binary tree node.
+class TreeNode
+    attr_accessor :val, :left, :right
+    def initialize(val)
+        @val = val
+        @left, @right = nil, nil
+    end
+end
+
+
+def aux(root, accum)
+  ret = 0
+  ret += aux(root.left, root.val + (accum * 10)) if root.left
+  ret += aux(root.right, root.val + (accum * 10)) if root.right
+
+  return ret if root.left or root.right
+
+  root.val + (accum * 10)
+end
+
+# @param {TreeNode} root
+# @return {Integer}
+def sum_numbers(root)
+  return 0 unless root
+  aux(root, 0)
+end
+
+# r = TreeNode.new(4)
+# r.left = TreeNode.new(9)
+# r.right = TreeNode.new(0)
+# r.left.left = TreeNode.new(5)
+# r.left.right = TreeNode.new(1)
+
+# sum_numbers(r)