Tower of Hanoi

game_of_hanoi.cpp

/*
 * Basic implementation of tower of hanoi
 *
 * Initial Board
 * 1 - -
 * 2 - -
 * 3 - -
 *
 * To win the board must be as below
 * - - 1
 * - - 2
 * - - 3
 *
 * Input is given from the command line the following format
 * # Meaning move time from stack 0 to stack 1
 * $ 0 1
 *
 * Author: Danish Rehman
 */

#include <iostream>
#include <cstring>
#include <stdio.h>

class GameOfHanoi{
    private:
        int board[3][3];
        int stack_top[3]; /*Maintains the index of top of the stack*/

        void update(int from, int to);
        bool move_not_allowed(int from, int to);
        void print_board();

    public:
        GameOfHanoi();
        bool is_winner();
        void move(int from, int to);

};

GameOfHanoi::GameOfHanoi()
{
    memset(board ,0, sizeof(board[0][0]) * 3 * 3);
    memset(stack_top ,0, sizeof(stack_top[0]) * 3 );

    board[0][0] = 1;
    board[1][0] = 2;
    board[2][0] = 3;

    stack_top[0] = 0;
    stack_top[1] = 3;
    stack_top[2] = 3;
}

void GameOfHanoi::print_board()
{
    for (int i = 0; i < 3; i++) {
        for (int j = 0; j < 3; j++) {
            if (board[i][j])
                std::cout << board[i][j] << " ";
            else
                std::cout << "-" << " ";
        }
        std::cout << "\n";
    }
}

bool GameOfHanoi::is_winner()
{
    // Check last stack for the exact pattern
    for (int i = 0; i < 3; i++)
    {
        if (board[i][2] != i + 1)
            return false;
    }

    return true;
}

bool GameOfHanoi:: move_not_allowed(int from, int to)
{
    /*
     * Check boundary conditions
     * Check if greater value tile is not being added over the lower value tile
     * in a given stack
     */
    if (from < 0 || from > 2 || to < 0 || to > 2 or stack_top[from] == 3)
        return true;

    if (stack_top[to] == 3 || (board[stack_top[to]][to] > board[stack_top[from]][from]))
        return false;

    return true;
}

void GameOfHanoi::update(int from, int to)
{
    /*
     * Move the tile and upate the respective
     * stack_top values
     */
    int from_top = board[stack_top[from]][from];
    board[stack_top[from]][from] = 0;
    stack_top[from]++;
    stack_top[to]--;
    board[stack_top[to]][to] = from_top;
}

void GameOfHanoi::move(int from, int to)
{
    if (move_not_allowed(from, to)) {
        std::cout << "Can’t move there.\n";
        return;
    }

    update(from, to);
    std::cout << "Piece moved and here is the board:\n";
    print_board();
}


int main()
{
    int from, to;
    GameOfHanoi game;
    std::cout << "WELCOME TO THE GAME: TOWER OF HANOI:\n";

    while (!game.is_winner()) {
        fflush (stdin);
        std::cout << "-----------------------------------------------------------------------\n";
        std::cout << "Enter from and to stack (space separated)\n";
        std::cout << "-----------------------------------------------------------------------\n";
        std::cin >> from >> to;
        game.move(from, to);
    }

    std::cout << "YOU WIN.GAME OVER\n";

    return 0;
}

README

How to compile

g++ game_of_hanoi.cpp

How to run

./a.out

Sample run

Enter from and to stack (space separated)
0 1
Piece moved and here is the board:

---

2 - -
3 1 -

Enter from and to stack (space separated)