/**Recursion Demo 3

 * @author TK Rogers

 * @version 11-06-09

 */

public class Mystry {

 

    public static void main ( ) {

      System.out.println ( mystry ( 3 ) ) ;

    }

   

    public static int mystry ( int y ) {

        System.out.println ( " y = " + y ) ;

        if (y == 0) {

            System.out.println ( " return x = " + 1 ) ;

            return 1 ;

        } else {

            System.out.println ( " else" ) ;

            int x = mystry ( y / 2 ) ; // y/2 is integer math so if y=3, y/2 = 1

         // y = 3 stored in stack ( x = 3 not "stacked"). Method re-run with y = 1

         // y = 1 stored in stack ( x = 0 not "stacked"). Method re-run with y = 0

         // The recursion stops and returns 1,

         // so that x = 1.The method then continues.

           

            System.out.println ( " x = " + x ) ;

            x *= x ;

            if ( y  %  2 == 1 ) x *= 3 ; // % is a modulus operator. It returns the

          // remainder of a division process. example 1: 3 % 2 = 1 because 2

    // goes into 3 once with a remainder of 1,  example 2: 5 % 2 = 1

    // because 2 goes into 5 twice with a remainder of 1,

    // example 3: 4 % 2 = 0

 

            System.out.println ( "return x = " + x ) ; 

            return x ;

      // The program now starts to use the y-values stored in the stack.

            // 1st time through  x = 1, y = 1   // 2nd time through x = 3, y = 3  

            // The stack with y values is now empty and the program quits,

            // having returned 27 back to the point where

            // the method was originally called.

        }

    }

}