feat(content): function signatures + test cases

backend/data/questions/convert-bst-to-greater-tree.yaml

@@ -9,6 +9,28 @@ patterns:
   - dfs
   - tree-traversal
 
+function_signature: "def convert_bst(root: TreeNode | None) -> TreeNode | None:"
+
+test_cases:
+  visible:
+    - input: { root: [4, 1, 6, 0, 2, 5, 7, null, null, null, 3, null, null, null, 8] }
+      expected: [30, 36, 21, 36, 35, 26, 15, null, null, null, 33, null, null, null, 8]
+    - input: { root: [0, null, 1] }
+      expected: [1, null, 1]
+  hidden:
+    - input: { root: [] }
+      expected: []
+    - input: { root: [5] }
+      expected: [5]
+    - input: { root: [2, 1, 3] }
+      expected: [5, 6, 3]
+    - input: { root: [5, 3, 8, 1, 4, 6, 9] }
+      expected: [33, 37, 17, 38, 34, 23, 9]
+    - input: { root: [1, null, 2, null, 3, null, 4] }
+      expected: [10, null, 9, null, 7, null, 4]
+    - input: { root: [-3, -4, -2] }
+      expected: [-5, -9, -2]
+
 description: |
   Given the `root` of a Binary Search Tree (BST), convert it to a Greater Tree such that every key of the original BST is changed to the original key plus the sum of all keys greater than the original key in BST.