programming language is JAVA: Write a public static method named static long fib

Question

programming language is JAVA:

Write a public static  method  named  static long fibFast(int n, long a, long b)

that returns the nth fibonacci number. The method should be coded as follows:

If n is zero then just return a (the zeroth fibonacci number).

If n > 0 call the function recursively with n-1 as the first parameter , b as the second parameter and a+b as the last parameter .

Effecfively, we are creating a loop in which a and b represent two consecutive fibonacci numbers. As n goes down by 1 we replace those by the next consecutive pair of Fibonacci numbers.

Eventually n reaches 0 and the first parameter will equal the nth fibonacci number.

Note: this only works if the initial call is fibFast(n, 0, 1).

Explanation / Answer

please find the method

static long fibFast(int n, long a, long b){
       if(n==0)
           return a;
       else
           return fibFast(n-1,b,a+b);
   }

and whole runnng code is

import java.util.Scanner;

public class Program {
   public static void main(String args[]){
       Scanner sc = new Scanner(System.in);
       System.out.println("Enter the value of n ");
       int num = sc.nextInt();
       long number = fibFast(num,0,1);
       System.out.println("nth fibonacci number is "+number);
   }
  
   static long fibFast(int n, long a, long b){
       if(n==0)
           return a;
       else
           return fibFast(n-1,b,a+b);
   }
}

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