feat(content): more test cases

backend/data/questions/four-sum.yaml

@@ -10,6 +10,22 @@ categories:
 patterns:
   - two-pointers
 
+function_signature: "def four_sum(nums: list[int], target: int) -> list[list[int]]:"
+
+test_cases:
+  visible:
+    - input: { nums: [1, 0, -1, 0, -2, 2], target: 0 }
+      expected: [[-2, -1, 1, 2], [-2, 0, 0, 2], [-1, 0, 0, 1]]
+    - input: { nums: [2, 2, 2, 2, 2], target: 8 }
+      expected: [[2, 2, 2, 2]]
+  hidden:
+    - input: { nums: [0, 0, 0, 0], target: 0 }
+      expected: [[0, 0, 0, 0]]
+    - input: { nums: [1, 2, 3, 4], target: 10 }
+      expected: [[1, 2, 3, 4]]
+    - input: { nums: [1, 2, 3, 4], target: 100 }
+      expected: []
+
 description: |
   Given an array `nums` of `n` integers, return *an array of all the **unique** quadruplets* `[nums[a], nums[b], nums[c], nums[d]]` such that: