feat(content): function signatures + test cases

backend/data/questions/build-an-array-with-stack-operations.yaml

@@ -9,6 +9,28 @@ categories:
 patterns:
   - two-pointers
 
+function_signature: "def build_array(target: list[int], n: int) -> list[str]:"
+
+test_cases:
+  visible:
+    - input: { target: [1, 3], n: 3 }
+      expected: ["Push", "Push", "Pop", "Push"]
+    - input: { target: [1, 2, 3], n: 3 }
+      expected: ["Push", "Push", "Push"]
+    - input: { target: [1, 2], n: 4 }
+      expected: ["Push", "Push"]
+  hidden:
+    - input: { target: [1], n: 1 }
+      expected: ["Push"]
+    - input: { target: [2], n: 2 }
+      expected: ["Push", "Pop", "Push"]
+    - input: { target: [3], n: 5 }
+      expected: ["Push", "Pop", "Push", "Pop", "Push"]
+    - input: { target: [1, 4], n: 5 }
+      expected: ["Push", "Push", "Pop", "Push", "Pop", "Push"]
+    - input: { target: [2, 3, 4], n: 4 }
+      expected: ["Push", "Pop", "Push", "Push", "Push"]
+
 description: |
   You are given an integer array `target` and an integer `n`.