feat(content): function signatures + test cases

backend/data/questions/append-characters-to-string-to-make-subsequence.yaml

@@ -10,6 +10,28 @@ patterns:
   - two-pointers
   - greedy
 
+function_signature: "def append_characters(s: str, t: str) -> int:"
+
+test_cases:
+  visible:
+    - input: { s: "coaching", t: "coding" }
+      expected: 4
+    - input: { s: "abcde", t: "a" }
+      expected: 0
+    - input: { s: "z", t: "abcde" }
+      expected: 5
+  hidden:
+    - input: { s: "abc", t: "abc" }
+      expected: 0
+    - input: { s: "abc", t: "d" }
+      expected: 1
+    - input: { s: "aaa", t: "aaaa" }
+      expected: 1
+    - input: { s: "xyz", t: "xyz" }
+      expected: 0
+    - input: { s: "abc", t: "axbxc" }
+      expected: 4
+
 description: |
   You are given two strings `s` and `t` consisting of only lowercase English letters.