feat(content): function signatures + test cases

backend/data/questions/break-a-palindrome.yaml

@@ -8,6 +8,30 @@ categories:
 patterns:
   - greedy
 
+function_signature: "def break_palindrome(palindrome: str) -> str:"
+
+test_cases:
+  visible:
+    - input: { palindrome: "abccba" }
+      expected: "aaccba"
+    - input: { palindrome: "a" }
+      expected: ""
+  hidden:
+    - input: { palindrome: "aa" }
+      expected: "ab"
+    - input: { palindrome: "aba" }
+      expected: "abb"
+    - input: { palindrome: "aaa" }
+      expected: "aab"
+    - input: { palindrome: "aaaa" }
+      expected: "aaab"
+    - input: { palindrome: "bab" }
+      expected: "aab"
+    - input: { palindrome: "abba" }
+      expected: "aaba"
+    - input: { palindrome: "zyzyz" }
+      expected: "ayzyz"
+
 description: |
   Given a palindromic string of lowercase English letters `palindrome`, replace **exactly one** character with any lowercase English letter so that the resulting string is **not** a palindrome and that it is the **lexicographically smallest** one possible.