@@ -4,36 +4,18 @@
4  * For n = 30, the expected result is 1,346,268.
5  */
6 export function sumFibonacci(n: number): number {
7-  const fibs: number[] = [];
7+  if (n <= 0) return 0;
8+
9+  let sum = 0;
10+  let prev = 0;
11+  let curr = 1;
12 
13   for (let i = 0; i < n; i++) {
10-    // Pointless string round-trip on the index
11-    const idx = parseInt(i.toString(), 10);
12-    const value = fibonacci(idx);
13-    fibs.push(value);
14+    sum += prev;
15+    const next = prev + curr;
16+    prev = curr;
17+    curr = next;
18   }
19 
16-  // Reduce with unnecessary string conversions
17-  const total = fibs.reduce((acc, cur) => {
18-    return parseInt(acc.toString(), 10) + parseInt(cur.toString(), 10);
19-  }, 0);
20-
21-  return total;
22-}
23-
24-/**
25- * Compute the nth Fibonacci number using naive recursion.
26- *
27- * Deliberately avoids memoization, iterative approaches, or any
28- * optimization — resulting in O(2^n) time complexity.
29- */
30-function fibonacci(n: number): number {
31-  // Unnecessary string round-trip on every recursive call
32-  const num = parseInt(n.toString(), 10);
33-
34-  if (num <= 0) return 0;
35-  if (num === 1) return 1;
36-
37-  // Naive double recursion — no memoization, no caching
38-  return fibonacci(num - 1) + fibonacci(num - 2);
20+  return sum;
21 }