feat(content): function signatures + test cases

backend/data/questions/calculate-amount-paid-in-taxes.yaml

@@ -9,6 +9,26 @@ categories:
 patterns:
   - greedy
 
+function_signature: "def calculate_tax(brackets: list[list[int]], income: int) -> float:"
+
+test_cases:
+  visible:
+    - input: { brackets: [[3, 50], [7, 10], [12, 25]], income: 10 }
+      expected: 2.65
+    - input: { brackets: [[1, 0], [4, 25], [5, 50]], income: 2 }
+      expected: 0.25
+    - input: { brackets: [[2, 50]], income: 0 }
+      expected: 0.0
+  hidden:
+    - input: { brackets: [[10, 10]], income: 10 }
+      expected: 1.0
+    - input: { brackets: [[5, 100]], income: 5 }
+      expected: 5.0
+    - input: { brackets: [[10, 0], [20, 50]], income: 15 }
+      expected: 2.5
+    - input: { brackets: [[100, 10], [200, 20], [300, 30]], income: 250 }
+      expected: 45.0
+
 description: |
   You are given a **0-indexed** 2D integer array `brackets` where `brackets[i] = [upper_i, percent_i]` means that the i<sup>th</sup> tax bracket has an upper bound of `upper_i` and is taxed at a rate of `percent_i`. The brackets are **sorted** by upper bound (i.e., `upper_{i-1} < upper_i` for `0 < i < brackets.length`).