Commit 646154d

@@ -0,0 +1,58 @@
+def assert_equal(x, y)
+  raise [x, y].inspect unless x == y
+end
+
+class Node
+  attr_accessor :left, :right, :value
+
+  def initialize(value)
+    @value = value
+  end
+end
+
+class Solution
+  def self.run(root, target, floor = nil, ceiling = nil)
+    return [floor, ceiling] if root == target
+
+    if target > root.value
+      if root.right
+        run(root.right, target, root.value, ceiling)
+      else
+        [root.value, ceiling]
+      end
+    else
+      if root.left
+        run(root.left, target, floor, root.value)
+      else
+        [floor, root.value]
+      end
+    end
+  end
+end
+
+=begin
+       8
+     /    \
+    4     12
+   / \   /  \
+  2   6 10  14
+
+=end
+
+root = Node.new(8)
+root.left = Node.new(4)
+root.right = Node.new(12)
+
+root.left.left = Node.new(2)
+root.left.right = Node.new(6)
+
+root.right.left = Node.new(10)
+root.right.right = Node.new(14)
+
+assert_equal([nil, 2], Solution.run(root, 1))
+assert_equal([2, 4], Solution.run(root, 3))
+assert_equal([4, 6], Solution.run(root, 5))
+assert_equal([10, 12], Solution.run(root, 11))
+assert_equal([12, 14], Solution.run(root, 13))
+assert_equal([14, nil], Solution.run(root, 15))
+puts "Yay!"