Pregunta de entrevista de Sasken

Here are two questions based on the topics mentioned: 1. **Arrays and Strings**: How would you reverse a string in Java without using built-in methods? Provide a solution that works by manipulating arrays. 2. **Data Structures and Algorithms (DSA)**: Implement a function to calculate the nth number in the Fibonacci series using recursion. Discuss its time complexity and how it can be optimized.