// Source code example for "A Practical Introduction
// to Data Structures and Algorithm Analysis"
// by Clifford A. Shaffer, Prentice Hall, 1998.
// Copyright 1998 by Clifford A. Shaffer

import java.io.*;

// Driver class for testing Fibonacci Number generators
class Fibmain {

// Two versions of a Fibonacci Number generator.
// The first is iterative.
// The second if recursive (and not very efficient!).
// Both are static since there is no object that they
//   can meaningfully act on.
static long fibi(int n) {    // Iterative Fibonacci generator
  Assert.notFalse((n>0) && (n<92), "Parameter out of range");
  long curr, prev;
  if ((n == 1) || (n == 2)) return 1;
  curr = prev = 1;           // curr holds current Fib value
  for (int i=3; i<=n; i++) { // Compute next value
    curr = prev + curr;
    prev = curr - prev;      // prev holds previous Fib value
  }
  return curr;
}
static long fibr(int n) { // Recursive Fibonacci generator
  Assert.notFalse((n>0) && (n<92), "Parameter out of range");
  if ((n == 1) || (n == 2)) return 1; // Base case
  return fibr(n-1) + fibr(n-2);       // Recursive call
}

  // Main function for the Fibonacci Number generator driver
  public static void main(String args[]) {
    Assert.notFalse(args.length == 1, "Usage: Fibmain <size>");
    int val = Integer.parseInt(args[0]);
  
    for (int i=1; i<=val; i++) {
      System.out.print("Doing " + i + ": Iterative Version "
					     + fibi(i));
      System.out.println("; Recursive Version " + fibr(i));
    }
    System.out.println("Now do fibi for 100");
    fibi(100); // This will fail Assert
    System.in.read();
  }

}