feat(content): function signatures + test cases

backend/data/questions/3sum-with-multiplicity.yaml

@@ -10,6 +10,28 @@ categories:
 patterns:
   - two-pointers
 
+function_signature: "def three_sum_multi(arr: list[int], target: int) -> int:"
+
+test_cases:
+  visible:
+    - input: { arr: [1, 1, 2, 2, 3, 3, 4, 4, 5, 5], target: 8 }
+      expected: 20
+    - input: { arr: [1, 1, 2, 2, 2, 2], target: 5 }
+      expected: 12
+    - input: { arr: [2, 1, 3], target: 6 }
+      expected: 1
+  hidden:
+    - input: { arr: [0, 0, 0], target: 0 }
+      expected: 1
+    - input: { arr: [0, 0, 0, 0, 0], target: 0 }
+      expected: 10
+    - input: { arr: [1, 2, 3, 4, 5, 6], target: 12 }
+      expected: 4
+    - input: { arr: [3, 3, 3, 3, 3], target: 9 }
+      expected: 10
+    - input: { arr: [1, 1, 1, 1, 1, 1], target: 3 }
+      expected: 20
+
 description: |
   Given an integer array `arr`, and an integer `target`, return the number of tuples `i, j, k` such that `i < j < k` and `arr[i] + arr[j] + arr[k] == target`.