Question

Write the Java source code necessary to build a solution for the problem below:

The Fibonacci numbers form a sequence where each number is the sum of the previous two numbers. Starting from 0 and 1, the first eight Fibonacci numbers are built in the following list using the equation Fn = Fn-1 + Fn-2:

0, 0
0, 1
1, 1
1, 2
2, 3
3, 5
5, 8
8, 13

The sequence would be the numbers in red (0, 1, 1, 2, 3, 5, 8, 13).

Create a stack class and a test program to display the first 50 Fibonacci numbers in descending order. Use a stack to store these numbers. Once 50 numbers have been computed, print the numbers in a descending order. You will note that this process is naturally recursive. Therefore, use recursion to find this series of Fibonacci numbers.

Answer 1

import java.util.Stack;

public class FibonacciDemo {

        public static long fib(int n) {
                long result;

                if (n < 2) {
                        result = n;
                } else {
                        result = fib(n - 1) + fib(n - 2);
                }

                return result;
        } // end fib

        public static void main(String[] args) {

                System.out.println("Wait a second.. It may take a minute of time!");
                Stack<Long> numbers = new Stack<>();
                for (int i = 0; i <= 50; i++) {
                        numbers.push(fib(i));
                }
                
                while(!numbers.isEmpty()) {
                        System.out.println(numbers.pop());
                }

        }

}

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Note: It may take upto 2-3 minutes to run this program.. since recursion is quite slow, and we are asked to use plain recursion.

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