feat(content): hidden test cases

backend/data/questions/subarray-sum-equals-k.yaml

@@ -26,6 +26,12 @@ test_cases:
       expected: 1
     - input: { nums: [1, -1, 0], k: 0 }
       expected: 3
+    - input: { nums: [3, 4, 7, 2, -3, 1, 4, 2], k: 7 }
+      expected: 4
+    - input: { nums: [0, 0, 0, 0], k: 0 }
+      expected: 10
+    - input: { nums: [1, 2, 3], k: 6 }
+      expected: 1
 
 description: |
   Given an array of integers `nums` and an integer `k`, return *the total number of subarrays whose sum equals to* `k`.