public class Hanoi {
/* This program displays the sequence of moves required to solve the
   Towers of Hanoi problem.  The problem requires n disks of different
   diameters placed on one of three pegs, with the largest disk on the
   bottom of the pile.  In a sequence of single-disk moves, the entire
   pile should be transferred to the third peg, with the additional
   proviso that at no time is a larger disk placed on top of a smaller 
   disk.  The third peg is used at each stage as an auxiliary peg. 
   
   The solution is done as a recursive method Move, which breaks the
   n-disk problem into two n-1 disk problems and a single disk move
   in between.  This is the essence of the "Divide and Conquer" strategy
   of problem solving.  */

static void Move( int nDisks, char StartPeg, char AuxPeg, char EndPeg) {
/*  This method recursively solves the problem for any number of
    disks nDisks, and any particular starting, ending, and auxiliary peg 
    Note that the roles of the pegs are changing with each recursive call. */

      if (nDisks == 1)    // base case -- stopping point for recursion
         System.out.println( "   Move disk from " + StartPeg + " to " + EndPeg); 
	  else  {             // recursive calls to Move with n - 1 disks

         // Move n - 1 disks from StartPeg to AuxPeg using EndPeg
            Move( nDisks - 1, StartPeg, EndPeg, AuxPeg );

         // Move 1 disk from StartPeg to EndPeg - no auxiliary peg needed
            Move( 1, StartPeg, ' ', EndPeg );

         // Move n - 1 disks from AuxPeg to EndPeg using StartPeg
            Move( nDisks - 1, AuxPeg, StartPeg, EndPeg );

      }
}

public static void main (String argv[]) {
   final char 	Peg1 = 'A',     // Identities of the three pegs
   			    Peg2 = 'B',
			    Peg3 = 'C';
   int   NumDisks;              // number of disks for the problem

   System.out.print( "Enter number of disks:  " );
   NumDisks = Keyboard.readInt();
   while(!Keyboard.eof()) {
      Move( NumDisks, Peg1, Peg2, Peg3 );
      System.out.print( "\nEnter number of disks:  " );
      NumDisks = Keyboard.readInt();
   }  
}

}