/********************************************

Filename:	towers.cpp
Author:		Grant Braught
Date:		3/30/98
Modified:	3/30/98 GWB

Purpose:

CS132 Dickinson College

Program that uses recursion to solve the towers
of Hanoi problem...

**********************************************/

#include <iostream>

// Function prototypes:
void getValues(int &numDisks, char &fromPeg, char &toPeg,
	       char &auxPeg);	
	// Read in the number of disks, the peg from
	// which the disk are moved and the peg to which
	// they are moved.
				
void SolveTowers(int numDisks, char fromPeg, 
		 char toPeg, char auxPeg);
	// Print out the steps requird to move numDisks from the
	// fromPeg to the toPeg using the auxPeg.
	
int main()
{
	int numDisks;
	char fromPeg;
	char toPeg;
	char auxPeg;
	
	getValues(numDisks,fromPeg,toPeg,auxPeg);	// Get the values...
	
	SolveTowers(numDisks, fromPeg, toPeg, auxPeg);
		// Solve the puzzle.
		
	// Main always returns 0.
	return 0;
}

void SolveTowers(int numDisks, char fromPeg, 
				 char toPeg, char auxPeg)
// Print out the steps requird to move numDisks from the
// fromPeg to the toPeg using the auxPeg.
{
	if (numDisks == 1)	// The problem is easy!
		cout << "Move disk 1 from " << fromPeg << " to "
		     << toPeg << "." << endl;
	
	else	// The problem is not so easy...
	{
		// Move N-1 disks from the fromPeg to the auxPeg
		// using the toPeg.
		SolveTowers(numDisks-1, fromPeg, auxPeg, toPeg);

		// Move the last disk from the fromPeg to the toPeg...
		cout << "Move disk " << numDisks << " from " << fromPeg 
		     << " to " << toPeg << "." << endl;
			 
		// Move the N-1 disks from the auxPeg to the toPeg 
		// using the fromPeg.
		SolveTowers(numDisks-1, auxPeg, toPeg, fromPeg);
	}
}

void getValues(int &numDisks, char &fromPeg, char &toPeg,
			   char &auxPeg)	
// Read in the number of disks, the peg from
// which the disk are moved and the peg to which
// they are moved.
{
	cout << "Solve the Towers of Hanoi problem..." << endl;
	
	cout << "Enter the number of Disks: ";
	cin >> numDisks;
	
	cout << "Enter the peg containing the disks [a,b,c]: ";
	cin >> fromPeg;
	
	cout << "Enter the peg to move the disks to [a,b,c]: ";
	cin >> toPeg;
	
	cout << "Enter the other peg [a,b,c]: ";
	cin >> auxPeg;
	
	// NOTE:  In reality this function should do some error checking.
	// It could check to make sure that the fromPeg and toPeg are
	// different and that they are valid.  It should
	// only offer the 2 remaining pegs when asking for the toPeg.
	// It could also determine the auxPeg automatically based on 
	// the other two. This would all improve the interface of 
	// the program.
}