Logic problem

Game card 9.js

var unshift = Array.prototype.unshift;
var splice = Array.prototype.splice;
var grid = [];
var used = [];
var new_grid = [];

grid.push([{type:"p", head : 1},{type:"c", head : 1},{type:"a", head : 2},{type:"o", head : 2}]);
grid.push([{type:"o", head : 1},{type:"a", head : 2},{type:"c", head : 2},{type:"p", head : 1}]);
grid.push([{type:"c", head : 1},{type:"p", head : 2},{type:"o", head : 2},{type:"a", head : 1}]);
grid.push([{type:"p", head : 1},{type:"c", head : 2},{type:"o", head : 2},{type:"a", head : 1}]);
grid.push([{type:"p", head : 2},{type:"c", head : 2},{type:"a", head : 1},{type:"c", head : 2}]);
grid.push([{type:"a", head : 1},{type:"p", head : 2},{type:"o", head : 2},{type:"p", head : 1}]);
grid.push([{type:"a", head : 1},{type:"o", head : 1},{type:"a", head : 2},{type:"c", head : 2}]);
grid.push([{type:"o", head : 1},{type:"a", head : 2},{type:"c", head : 2},{type:"p", head : 1}]);
grid.push([{type:"p", head : 1},{type:"c", head : 2},{type:"o", head : 2},{type:"a", head : 1}]);

Array.prototype.shuffle = function() {
   var i = this.length;
   while (--i) {
      var j = Math.floor(Math.random() * (i + 1))
      var temp = this[i];
      this[i] = this[j];
      this[j] = temp;
   }

   return this; // for convenience, in case we want a reference to the array
};

Array.prototype.rotate = (function() {
    return function(count) {
        var len = this.length;
        unshift.apply(this, splice.call(this, count % len, len));
        return this;
    };
})();

function checkValidity(try_card, position, orientation) {
    // since I'm adding from top left to bottom, I only need to check top and left
		var valid = true;
		// top
		if (typeof new_grid[position-3] != "undefined") { 
			if (try_card[0].type != new_grid[position-3][2].type) valid = false;
			if (try_card[0].head == new_grid[position-3][2].head) valid = false;
		}
	  // left
		if (typeof new_grid[position-1] != "undefined") { 
			if (try_card[3].type != new_grid[position-1][1].type) valid = false;
			if (try_card[3].head == new_grid[position-1][1].head) valid = false;
		}
	return valid;
}

function addCard(whichPos) {
 for (card = 0; card < 9; card++) {
		if (!used[card]) {
      for (orientation = 0; orientation < 4; orientation++) {
          try_card = temp_grid[card].rotate(orientation);
          if (checkValidity(try_card, whichPos, orientation)) { 
              used[card] = true;
              new_grid.push(try_card);
              if (whichPos < 8) {
								addCard(whichPos + 1);
                break;
							} else {
								console.log("I WON");
                console.log(JSON.stringify(used));
                console.log(new_grid.length);
                console.log(JSON.stringify(new_grid));
							}
//          } else {
//						if (orientation == 3 && card == 8)  console.log("lost");
					}       
          
      }
		}
	}  
}


for (j = 0; j<100000000; j++) {
  // randomize array first
  var temp_grid = grid.shuffle();
  // randomize rotations
  for (i = 0; i<9; i++) {
    var random = Math.floor(Math.random()*4);
     temp_grid[i].rotate(random);
  }
  // reset new_grid
  new_grid = [];
  // reset used cards
  used = [false, false, false,false, false, false,false, false, false];
  //start try
  addCard(0);

}

Et pour check les values rendues : https://gist.github.com/836019