Commit 8283923

@@ -0,0 +1,48 @@
+description = <<-DESC
+Given a binary tree and a number k, your task is to find the sum of tree nodes at level k. The binary tree is represented by a string tree with the format: (<node-value>(<left subtree>)(<right subtree>)).
+
+Example
+
+For tree = "(0(5(6()())(14()(9()())))(7(1()())(23()())))" and k = 2, the output should be
+
+treeLevelSum(tree, k) = 44.
+
+Explanation: The nodes at level 2 are 6, 14, 1, and 23, so the answer is 6 + 14 + 1 + 23 = 44.
+
+Input/Output
+
+[time limit] 4000ms (rb)
+[input] string tree
+
+A valid string representing a tree.
+
+Guaranteed constraints:
+
+2 ≤ tree.length ≤ 105.
+
+All the values in a given tree are guaranteed to be integers.
+
+[input] integer k
+
+Guaranteed constraints:
+
+0 ≤ k ≤ 105.
+
+[output] integer
+
+The total sum of all the values at level k in a tree.
+DESC
+
+describe "tree_level_sum" do
+  def tree_level_sum(tree, level)
+    0
+  end
+
+  [
+    ["(0(5(6()())(14()(9()())))(7(1()())(23()())))", 2, 44],
+  ].each do |(tree, level, expected)|
+    it do
+      expect(tree_level_sum(tree, level)).to eql(expected)
+    end
+  end
+end