fifteen.c

/**
 * fifteen.c
 *
 * Implements Game of Fifteen (generalized to d x d).
 *
 * Usage: fifteen d
 *
 * whereby the board's dimensions are to be d x d,
 * where d must be in [DIM_MIN,DIM_MAX]
 *
 * Note that usleep is obsolete, but it offers more granularity than
 * sleep and is simpler to use than nanosleep; `man usleep` for more.
 */
 
#define _XOPEN_SOURCE 500

#include <cs50.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

// constants
#define DIM_MIN 3
#define DIM_MAX 9

//variables to keep track of the blank tile
int bx,by;

// board
int board[DIM_MAX][DIM_MAX];

// dimensions
int d;

// prototypes
void clear(void);
void greet(void);
void init(void);
void draw(void);
bool move(int tile);
bool won(void);

int main(int argc, string argv[])
{
    // ensure proper usage
    if (argc != 2)
    {
        printf("Usage: fifteen d\n");
        return 1;
    }

    // ensure valid dimensions
    d = atoi(argv[1]);
    if (d < DIM_MIN || d > DIM_MAX)
    {
        printf("Board must be between %i x %i and %i x %i, inclusive.\n",
            DIM_MIN, DIM_MIN, DIM_MAX, DIM_MAX);
        return 2;
    }

    // open log
    FILE *file = fopen("log.txt", "w");
    if (file == NULL)
    {
        return 3;
    }


    bx=d-1;
    by=d-1;
    // greet user with instructions
    greet();

    // initialize the board
    init();

    // accept moves until game is won
    while (true)
    {
        // clear the screen
        clear();

        // draw the current state of the board
        draw();

        // log the current state of the board (for testing)
        for (int i = 0; i < d; i++)
        {
            for (int j = 0; j < d; j++)
            {
                fprintf(file, "%i", board[i][j]);
                if (j < d - 1)
                {
                    fprintf(file, "|");
                }
            }
            fprintf(file, "\n");
        }
        fflush(file);

        // check for win
        if (won())
        {
            printf("ftw!\n");
            break;
        }

        // prompt for move
        printf("Tile to move: ");
        int tile = get_int();
        
        // quit if user inputs 0 (for testing)
        if (tile == 0)
        {
            break;
        }

        // log move (for testing)
        fprintf(file, "%i\n", tile);
        fflush(file);

        // move if possible, else report illegality
        if (!move(tile))
        {
            printf("\nIllegal move.\n");
            usleep(500000);
        }

        // sleep thread for animation's sake
        usleep(500000);
    }
    
    // close log
    fclose(file);

    // success
    return 0;
}

/**
 * Clears screen using ANSI escape sequences.
 */
void clear(void)
{
    printf("\033[2J");
    printf("\033[%d;%dH", 0, 0);
}

/**
 * Greets player.
 */
void greet(void)
{
    clear();
    printf("WELCOME TO GAME OF FIFTEEN\n");
    usleep(2000000);
}

/**
 * Initializes the game's board with tiles numbered 1 through d*d - 1
 * (i.e., fills 2D array with values but does not actually print them).  
 */
void init(void)
{
    int o,p;
    int max=d*d;
    for(o=0;o<d;o++)
    {
        for(p=0;p<d;p++)
        {
            board[o][p]=max-1;
            max--;
        }
    }
    if(d%2==0)
    {
        board[d-1][d-2] = 2;
        board[d-1][d-3] = 1;
    }
}

/**
 * Prints the board in its current state.
 */
void draw(void)
{
    int o,p;
    for(o=0;o<d;o++)
    {
        for(p=0;p<d;p++)
        {
            if(board[o][p]>9)
            {
                printf("%i",board[o][p]);
            }
            else if (board[o][p] > 0)
            {
                printf("%2i ",board[o][p]);
            }
                
            else
                printf(" _");

        }
        printf("\n");
    }
}

/**
 * If tile borders empty space, moves tile and returns true, else
 * returns false. 
 */
bool move(int tile)
{
    int o,p,tx,ty;
    for(o=0;o<d;o++)
    {
        for(p=0;p<d;p++)
        {
            if(board[o][p]==tile)
            {
                tx=o;
                ty=p;
                break;
            }
        }
    }
    if ((tile == board[bx+1][by] && bx < 3) ||(tile ==  board[bx-1][by] && bx > -1)|| 
    (tile ==  board[bx][by+1] && by < 3)|| (tile == board[bx][by-1] && by > -1))  
    {
        board[tx][ty] = 0;   //switches tiles on gameboard
        board[bx][by] = tile;
          
        bx = tx;      //moves the blanks location in global variable
        by = ty;
        
        return true;
    }
    else 
        return false;
}

/**
 * Returns true if game is won (i.e., board is in winning configuration), 
 * else false.
 */
bool won(void)
{
    int o,p;
    int counter=1;
    for(o=0;o<d;o++)
    {
        for(p=0;p<d;p++)
        {
            if (board[o][p] == 0)
                counter = 0;
                       
            if (board[o][p] != counter)  //checks if all the other values are where they are supposed to be                 
                return false; 
            counter++;
        }
    }
    return true;
}