feat(content): function signatures + test cases

backend/data/questions/unique-number-of-occurrences.yaml

@@ -9,6 +9,26 @@ categories:
 patterns:
   - prefix-sum
 
+function_signature: "def unique_occurrences(arr: list[int]) -> bool:"
+
+test_cases:
+  visible:
+    - input: { arr: [1, 2, 2, 1, 1, 3] }
+      expected: true
+    - input: { arr: [1, 2] }
+      expected: false
+    - input: { arr: [-3, 0, 1, -3, 1, 1, 1, -3, 10, 0] }
+      expected: true
+  hidden:
+    - input: { arr: [1] }
+      expected: true
+    - input: { arr: [1, 1, 1] }
+      expected: true
+    - input: { arr: [1, 1, 2, 2] }
+      expected: false
+    - input: { arr: [1, 2, 3] }
+      expected: false
+
 description: |
   Given an array of integers `arr`, return `true` *if the number of occurrences of each value in the array is **unique***, or `false` *otherwise*.