feat(content): function signatures + test cases

backend/data/questions/greatest-common-divisor-of-strings.yaml

@@ -9,6 +9,30 @@ categories:
 patterns:
   - greedy
 
+function_signature: "def gcd_of_strings(str1: str, str2: str) -> str:"
+
+test_cases:
+  visible:
+    - input: { str1: "ABCABC", str2: "ABC" }
+      expected: "ABC"
+    - input: { str1: "ABABAB", str2: "ABAB" }
+      expected: "AB"
+    - input: { str1: "LEET", str2: "CODE" }
+      expected: ""
+  hidden:
+    - input: { str1: "A", str2: "A" }
+      expected: "A"
+    - input: { str1: "AAAAAA", str2: "AAA" }
+      expected: "AAA"
+    - input: { str1: "ABAB", str2: "AB" }
+      expected: "AB"
+    - input: { str1: "AB", str2: "BA" }
+      expected: ""
+    - input: { str1: "TAUXXTAUXXTAUXXTAUXXTAUXX", str2: "TAUXXTAUXXTAUXXTAUXXTAUXXTAUXX" }
+      expected: "TAUXX"
+    - input: { str1: "ABCDEF", str2: "ABC" }
+      expected: ""
+
 description: |
   For two strings `s` and `t`, we say "`t` divides `s`" if and only if `s = t + t + t + ... + t` (i.e., `t` is concatenated with itself one or more times).