Complete Fib

public int Fib( int N )
{
  if       ( N==1 ) 
    return 1;
    
  else if  ( N==2 ) 
    return 1;
    
  else
    return Fib( N-1 ) + Fib( N-2 );
}

It may worry you that the code for Fib(int N) uses Fib(N-1) and Fib(N-2). This is fine. Look at the math-like definition. Play with it until you understand it. The program says the same thing but uses a different language (Java) to say it.

It is the job of the Java system to make sure that you get the computation that you ask for.