Implement Fibonacci

fibonacci.py

@@ -0,0 +1,26 @@
+def fibonacci(n: int):
+    """Return the n-th Fibonacci number."""
+
+    memo: dict[int, int] = {}
+    """The memoization register."""
+
+    def dp(i: int):
+        """Recursive subproblem: return memoized i-th Fibonacci number."""
+
+        # check if memoized yet
+        f = memo.get(i, None)
+        if f is not None:
+            return f
+
+        # compute actual value, making "free" recursive calls
+        f = 2 if i <= 2 else dp(i-1) + dp(i-2)
+
+        # set the memoization register
+        memo[i] = f
+
+        return f
+
+    return dp(n)
+
+
+print(f"The 9th Fibonacci number is: {fibonacci(9)}")