👀 Views: 0 💬 Answers: 1 📅 Created: 2025-06-12

java algorithm recursion Java

Hey everyone, I'm running into an issue that's driving me crazy. I'm currently working on a project where I need to compute Fibonacci numbers recursively in Java. While I understand that the straightforward recursive approach has exponential time complexity, I wanted to explore it for educational purposes. However, I've noticed that for relatively small inputs (like `n = 30`), the computation takes significantly longer than expected. I’m using Java 17 and attempting to calculate `fib(n)` as follows: ```java public class Fibonacci { public static int fib(int n) { if (n <= 1) return n; return fib(n - 1) + fib(n - 2); } public static void main(String[] args) { System.out.println(fib(30)); } } ``` When I run this, it finishes, but it takes over 30 seconds to compute. This seems like an excessive amount of time for such a small input. I realize that memoization or using an iterative approach would be more optimal, but I want to understand why this naive recursive method performs so poorly. Is there something about the Java runtime that amplifies the inefficiency? Also, how does the underlying stack management in Java affect the execution time for deep recursion? Any insights or suggestions would be greatly appreciated! I'm working on a CLI tool that needs to handle this. Am I missing something obvious?