feat(content): hidden test cases

backend/data/questions/check-if-word-equals-summation-of-two-words.yaml

@@ -8,6 +8,26 @@ categories:
 patterns:
   - greedy
 
+function_signature: "def is_sum_equal(first_word: str, second_word: str, target_word: str) -> bool:"
+
+test_cases:
+  visible:
+    - input: { first_word: "acb", second_word: "cba", target_word: "cdb" }
+      expected: true
+    - input: { first_word: "aaa", second_word: "a", target_word: "aab" }
+      expected: false
+    - input: { first_word: "aaa", second_word: "a", target_word: "aaaa" }
+      expected: true
+  hidden:
+    - input: { first_word: "a", second_word: "a", target_word: "aa" }
+      expected: false
+    - input: { first_word: "j", second_word: "j", target_word: "bi" }
+      expected: true
+    - input: { first_word: "ab", second_word: "cd", target_word: "ef" }
+      expected: false
+    - input: { first_word: "a", second_word: "b", target_word: "b" }
+      expected: true
+
 description: |
   The **letter value** of a letter is its position in the alphabet **starting from 0** (i.e. `'a' -> 0`, `'b' -> 1`, `'c' -> 2`, etc.).