Fibbonacci.java

import java.util.HashMap;

public class factorial {

	private static double sqrt5 = Math.sqrt(5);
	private static double Phi = (1 - sqrt5) / 2;
	private static double phi = (1 + sqrt5) / 2;

	public static boolean isInteger(String s) {
		return isInteger(s, 10);
	}

	public static boolean isInteger(String s, int radix) {
		if (s.isEmpty())
			return false;
		for (int i = 0; i < s.length(); i++) {
			if (i == 0 && s.charAt(i) == '-') {
				if (s.length() == 1)
					return false;
				else
					continue;
			}
			if (Character.digit(s.charAt(i), radix) < 0)
				return false;
		}
		return true;
	}

	public record fib_out(long fib, HashMap<Long, Long> memo) {
	}

	public static long fib_binet(long n) {
		return Math.round(Math.pow(Phi, n) - Math.pow(phi, n) / sqrt5);
	}

	public static fib_out fib_memo(long n, HashMap<Long, Long> memo) {
		if (memo.containsKey(n)) {
			return new fib_out(memo.get(n), memo);
		}
		if (n < 1) {
			return new fib_out(1, memo);
		}
		fib_out val_1 = fib_memo(n - 1, memo);
		val_1.memo.put(n - 1, val_1.fib);
		fib_out val_2 = fib_memo(n - 2, val_1.memo);
		val_2.memo.put(n - 2, val_2.fib);
		return new fib_out(val_1.fib + val_2.fib, val_2.memo);
	}

	public static long fib(long n) {
		if (n < 1) {
			return 1;
		}
		return fib(n - 1) + fib(n - 2);
	}

	enum Speed {
		fast,
		instant,
		slow
	}

	public static void main(String[] args) {
		int n = 50;
		Speed speed = Speed.slow;
		if (args.length == 1 && isInteger(args[0])) {
			n = Integer.parseInt(args[0]);
			System.out.println("Finding Fibonacci numbers with no optimizations till: " + n);
		} else if (args.length == 1 && (args[0].equals("-f") || args[0].equals("--fast"))) {
			System.out.println("Finding Fibonacci numbers with memoization till: " + n);
			speed = Speed.fast;
		} else if (args.length == 1 && (args[0].equals("-i") || args[0].equals("--instant"))) {
			System.out.println("Finding Fibonacci numbers instantly till: " + n);
			speed = Speed.instant;
		} else if (args.length == 2 && (args[0].equals("-f") || args[0].equals("--fast"))) {
			n = Integer.parseInt(args[1]);
			System.out.println("Finding Fibonacci numbers with memoization till: " + n);
			speed = Speed.fast;
		} else if (args.length == 2 && (args[0].equals("-i") || args[0].equals("--instant"))) {
			n = Integer.parseInt(args[1]);
			System.out.println("Finding Fibonacci numbers instantly till: " + n);
			speed = Speed.instant;
		}
		System.out.println("fibonacci number, time taken in nanosecs to find the number ");
		HashMap<Long, Long> memo = new HashMap<Long, Long>();
		for (int i = 0; i < n; i++) {
			long start = System.nanoTime();
			switch (speed) {
				case fast:
					System.out.println(i + ", " + fib_memo(i, memo).fib + "," + (System.nanoTime() - start));
					break;

				case slow:
					System.out.println(fib(i) + "," + (System.nanoTime() - start));
					break;

				case instant:
					System.out.println(fib_binet(i) + "," + (System.nanoTime() - start));
					break;

				default:
					System.out.println(fib(i) + "," + (System.nanoTime() - start));
					break;
			}

		}

	}
}

CPU: AMD Ryzen 5 4600H with Radeon Graphics
Memory: 15363MiB