Sliding tiles puzzle

1

I made a sliding tiles puzzle game (based on the example in Gary Rozenweig’s Actionscript for games book.
It has 15 tiles (54 pixel squares) and works realy well. But I have been asked to make a simpler version with only 8 tiles and I am struggling to adapt the code. I can’t get the pieces in the right place and they don’t behave properly any more!
I 'd be really grateful for any advice - I can only do simple AS so far, but am trying to get to grips with it. Many thanks for some help.

This is the code:
function initGame () {
// set the horizontal and vertical distance
// between tiles
tileDist = 54;

// set all tiles in exactly the correct spot
for (x=1;x<=4;x++) {
	for (y=0;y<=3;y++) {
		tile = x+y*4;
		_root["tile"+tile]._x = x*tileDist;
		_root["tile"+tile]._y = y*tileDist+tileDist;
	}
}

// make 100 random but valid moves
for(tilenum=0;tilenum<100;tilenum++) {
	do {
		// pick a random tile
		tile = "tile"+(random(15)+1);
		// see whether there is an empty space near it
		emptySpace = findEmpty(tile);
	// keep looping until a tile is found that
	// has an empty space near it
	} while ( emptySpace == "none" );

	// move this tile to the empty space
	moveTile(tile,findEmpty(tile));			
}

}

// given a tile, see if the empty space is near it
function findEmpty (tile) {
// get location of tile
tilex = _root[tile]._x;
tiley = _root[tile]._y;

// see whether there is a tile to the left
if (tilex > tileDist) {
	if (!tileThere(tilex-tileDist, tiley)) {
		return("left");
	}
}

// see whether there is a tile to the right
if (tilex < tileDist*4) {
	if (!tileThere(tilex+tileDist, tiley)) {
		return("right");
	}
}

// see whether there is a tile above
if (tiley > tileDist) {
	if (!tileThere(tilex, tiley-tileDist)) {
		return("above");
	}
}

// see whether there is a tile below
if (tiley < tileDist*4) {
	if (!tileThere(tilex, tiley+tileDist)) {
		return("below");
	}
}

// tiles are in all directions
return("none");

}

// check to see whether there is a tile at a certain location
function tileThere (thisx, thisy) {
// loop through tiles
for (i=1;i<=15;i++) {
// see if x matches
if (_root[“tile”+i]._x == thisx) {
// se if y matches
if (_root[“tile”+i]._y == thisy) {
return true;
}
}
}

// no tile there
return false;

}

// move a tile in a certain direction
function moveTile (tile, direction) {
if (direction == “above”) {
_root[tile]._y -= tileDist;
} else if (direction == “below”) {
_root[tile]._y += tileDist;
} else if (direction == “left”) {
_root[tile]._x -= tileDist;
} else if (direction == “right”) {
_root[tile]._x += tileDist;
}
}

// utility function to see on which tile the
// player clicked
function tileUnderMouse () {
for (i=1; i<=15; i++) {
if (_root[“Tile”+i].hitTest(_xmouse, _ymouse)) {
return (i);
}
}
}

initGame();
stop();