/**

• fifteen.c
• Computer Science 50
• Problem Set 3
• Implements the 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 [MIN,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• Note that usleep is obsolete, but it offers more granularity than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>

// board's minimal dimension #define MIN 3

// board's maximal dimension #define MAX 9

// board, whereby board[i][j] represents row i and column j int board[MAX][MAX];

// board's dimension int d;

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

int main(int argc, string argv[]) { // greet player greet();

// ensure proper usage
if (argc != 2)
{
    printf("Usage: ./fifteen d\n");
    return 1;
}

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

// initialize the board
init();

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

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

    // saves the current state of the board (for testing)
    save();

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

    // prompt for move
    printf("Tile to move: ");
    int tile = GetInt();

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

    // sleep for animation's sake
    usleep(500000);
}

// that's all folks
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("GAME OF FIFTEEN\n"); usleep(2000000); }

/**

• Initializes the game's board with tiles numbered 1 through d*d - 1,
• (i.e., fills board with values but does not actually print them),
• whereby board[i][j] represents row i and column j. */ void init(void) { // define a counter and populate the array int c = 1; for (int i = 0; i < d; i++) { for (int j = 0; j < d; j++) { // fill the tiles in descending order board[i][j] = d * d - c; c++; } } //make the last tile blank board[d-1][d-1] = 0; // if there are an odd number of tiles, switch 1 and 2 if ((d * 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) { for (int i = 0; i < d; i++) { for (int j = 0; j < d; j++) {if (board[i][j] == 0) // print the blank tile printf(" _"); else // the tiles in descending order printf("%2d", board[i][j]); } printf("\n"); } }

/**

• If tile borders empty space, moves tile and returns true, else

• returns false. */ bool move(int tile) { // establish algorithm for checking bordering tiles for (int i = 0; i < d; i++) { for (int j = 0; j < d; j++) { if (board[i][j] == tile) { //check if the blank is to the right if (j+1 <= d-1 && board[i][j+1] == 0) { board[i][j+1] = tile; board[i][j] = 0; return true; } // check if the blank is to the left else if (j-1 >= 0 && board[i][j-1] == 0) { board[i][j-1] = tile; board[i][j] = 0; return true; } // check if the blank is above else if (i-1 >= 0 && board[i-1][j] == 0) { board[i-1][j] = tile; board[i][j] = 0; return true; } // check if the blank is below else if (i+1 <= d-1 && board[i+1][j] == 0) { board[i+1][j] = tile; board[i][j] = 0; return true; }

       }
   }
  

  } return false; }

/**

• Returns true if game is won (i.e., board is in winning configuration),

• else false. */ bool won(void) { // check if board is sorted int n = 1;

  // check to see if last tile is blank and return false if it is not if (board[d-1][d-1] != 0) return false;

  // set up for loops to check if numbers are in ascending order beginning with 1 for (int i = 0; i < d; i++) { for (int j = 0; j < d; j++) { // check last grid position first, if blank, return true if (i == d - 1 && j == d - 1) return true;

       // check the numbers on the rest of the tiles
       if (n != board[i][j])
           return false;
       n++;                        
   }
  

  } return false; }

/**

• Saves the current state of the board to disk (for testing). */ void save(void) { // log const string log = "log.txt";

  // delete existing log, if any, before first save static bool saved = false; if (!saved) { unlink(log); saved = true; }

  // open log FILE* p = fopen(log, "a"); if (p == NULL) { return; }

  // log board fprintf(p, "{"); for (int i = 0; i < d; i++) { fprintf(p, "{"); for (int j = 0; j < d; j++) { fprintf(p, "%i", board[i][j]); if (j < d - 1) { fprintf(p, ","); } } fprintf(p, "}"); if (i < d - 1) { fprintf(p, ","); } } fprintf(p, "}\n");

  // close log fclose(p); }

**:) fifteen.c exists

:) fifteen.c compiles

:( init initializes 3x3 board correctly

\ expected file to be of length 18, not 26

:( init initializes 4x4 board correctly

\ expected file to be of length 38, not 48**