feat(content): function signatures + test cases

backend/data/questions/interleaving-string.yaml

@@ -9,6 +9,32 @@ categories:
 patterns:
   - dynamic-programming
 
+function_signature: "def is_interleave(s1: str, s2: str, s3: str) -> bool:"
+
+test_cases:
+  visible:
+    - input: { s1: "aabcc", s2: "dbbca", s3: "aadbbcbcac" }
+      expected: true
+    - input: { s1: "aabcc", s2: "dbbca", s3: "aadbbbaccc" }
+      expected: false
+    - input: { s1: "", s2: "", s3: "" }
+      expected: true
+  hidden:
+    - input: { s1: "a", s2: "b", s3: "ab" }
+      expected: true
+    - input: { s1: "a", s2: "b", s3: "ba" }
+      expected: true
+    - input: { s1: "abc", s2: "def", s3: "abcdef" }
+      expected: true
+    - input: { s1: "", s2: "abc", s3: "abc" }
+      expected: true
+    - input: { s1: "abc", s2: "", s3: "abc" }
+      expected: true
+    - input: { s1: "a", s2: "b", s3: "abc" }
+      expected: false
+    - input: { s1: "aaa", s2: "aaa", s3: "aaaaaa" }
+      expected: true
+
 description: |
   Given strings `s1`, `s2`, and `s3`, find whether `s3` is formed by an **interleaving** of `s1` and `s2`.