1 "use strict";

     2 

     3 var board = {};

     4 board.create = function() {

     5     var brd = [];

     6     for (var i = 0; i < 4; i++) {

     7         brd[i] = [];

     8         for (var j = 0; j < 4; j++) {

     9             brd[i][j] = 0;

    10         }

    11     }

    12     return brd;

    13 }

    14 board.copy = function(from, to) {

    15     for (var i = 0; i < 4; i++) {

    16         for (var j = 0; j < 4; j++) {

    17             to[i][j] = from[i][j];

    18         }

    19     }

    20 }

    21 board.freeCnt = function(brd) {

    22     var cnt = 0;

    23     for (var i = 0; i < 4; i++) {

    24         for (var j = 0; j < 4; j++) {

    25             if (brd[i][j] === 0)

    26                 cnt++;

    27         }

    28     }

    29     return cnt;

    30 }

    31 board.gameOver = function(brd) {

    32     if (board.freeCnt(brd) > 0)

    33         return false;

    34     for (var i = 0; i < 4; i++) {

    35         for (var j = 0; j < 3; j++) {

    36             if (brd[i][j] === brd[i][j+1])

    37                 return false;

    38         }

    39     }

    40     for (var j = 0; j < 4; j++) {

    41         for (var i = 0; i < 3; i++) {

    42             if (brd[i][j] === brd[i+1][j])

    43                 return false;

    44         }

    45     }

    46     return true;

    47 }

    48 board.putRandom = function(brd) {

    49     var cnt = board.freeCnt(brd);

    50     cnt = Math.floor(Math.random() * cnt)+1;

    51     for (var i = 0; i < 4 && cnt > 0; i++) {

    52         for (var j = 0; j < 4 && cnt > 0; j++) {

    53             if (brd[i][j] !== 0)

    54                 continue;

    55             if (cnt === 1)

    56                 brd[i][j] = (Math.random() > .9) ? 2 : 1;

    57             cnt--;

    58         }

    59     }

    60 }

    61 /* http://www.reddit.com/r/2048/comments/214njx/highest_possible_score_for_2048_warning_math */

    62 var boardScoreTbl = [0];

    63 for (var i = 1, exp = 2; i < 16; i++, exp *= 2) {

    64     boardScoreTbl[i] = (i-1)*exp;

    65 }

    66 board.score = function(brd) {

    67     var score = 0;

    68     var max = 0;

    69     for (var i = 0; i < 4; i++) {

    70         for (var j = 0; j < 4; j++) {

    71             var val = brd[i][j];

    72             score += boardScoreTbl[val];

    73             if (max < val)

    74                 max = val;

    75         }

    76     }

    77     return {score: score, max: Math.pow(2, max)};

    78 }

    79 

    80 board.row = {};

    81 board.row.init = function() {

    82     return {stack: [], curr: 0};

    83 }

    84 board.row.push = function(state, val) {

    85     if (val === 0)

    86         return;

    87     if (state.curr === 0) {

    88         state.curr = val;

    89         return;

    90     }

    91     if (state.curr === val) {

    92         state.stack.push(state.curr+1);

    93         state.curr = 0;

    94     } else {

    95         state.stack.push(state.curr);

    96         state.curr = val;

    97     }

    98 }

    99 board.row.finish = function(state) {

   100     if (state.curr !== 0)

   101         state.stack.push(state.curr);

   102 }

   103 board.move = {};

   104 board.move.up = function(brd) {

   105     var updated = false;

   106     for (var j = 0; j < 4; j++) {

   107         var state = board.row.init();

   108         for (var i = 0; i < 4; i++) {

   109             board.row.push(state, brd[i][j]);

   110         }

   111         board.row.finish(state);

   112         for (var i = 0; i < state.stack.length; i++) {

   113             if (brd[i][j] !== state.stack[i])

   114                 updated = true;

   115             brd[i][j] = state.stack[i];

   116         }

   117         for (; i < 4; i++) {

   118             if (brd[i][j] !== 0)

   119                 updated = true;

   120             brd[i][j] = 0;

   121         }

   122     }

   123     return updated;

   124 };

   125 board.move.down = function(brd) {

   126     var updated = false;

   127     for (var j = 0; j < 4; j++) {

   128         var state = board.row.init();

   129         for (var i = 3; i >= 0; i--) {

   130             board.row.push(state, brd[i][j]);

   131         }

   132         board.row.finish(state);

   133         for (var i = 0; i < state.stack.length; i++) {

   134             if (brd[3-i][j] !== state.stack[i])

   135                 updated = true;

   136             brd[3-i][j] = state.stack[i];

   137         }

   138         for (; i < 4; i++) {

   139             if (brd[3-i][j] !== 0)

   140                 updated = true;

   141             brd[3-i][j] = 0;

   142         }

   143     }

   144     return updated;

   145 };

   146 board.move.left = function(brd) {

   147     var updated = false;

   148     for (var i = 0; i < 4; i++) {

   149         var state = board.row.init();

   150         for (var j = 0; j < 4; j++) {

   151             board.row.push(state, brd[i][j]);

   152         }

   153         board.row.finish(state);

   154         for (var j = 0; j < state.stack.length; j++) {

   155             if (brd[i][j] !== state.stack[j])

   156                 updated = true;

   157             brd[i][j] = state.stack[j];

   158         }

   159         for (; j < 4; j++) {

   160             if (brd[i][j] !== 0)

   161                 updated = true;

   162             brd[i][j] = 0;

   163         }

   164     }

   165     return updated;

   166 };

   167 board.move.right = function(brd) {

   168     var updated = false;

   169     for (var i = 0; i < 4; i++) {

   170         var state = board.row.init();

   171         for (var j = 3; j >= 0; j--) {

   172             board.row.push(state, brd[i][j]);

   173         }

   174         board.row.finish(state);

   175         for (var j = 0; j < state.stack.length; j++) {

   176             if (brd[i][3-j] !== state.stack[j])

   177                 updated = true;

   178             brd[i][3-j] = state.stack[j];

   179         }

   180         for (; j < 4; j++) {

   181             if (brd[i][3-j] !== 0)

   182                 updated = true;

   183             brd[i][3-j] = 0;

   184         }

   185     }

   186     return updated;

   187 };