scrabble array simplified

gistfile1.txt

<?php
header('Content-type: text/html; charset=utf-8');
mb_internal_encoding("UTF-8");
ini_set('memory_limit', '1024M');
ini_set('max_execution_time', 500);
?>
    <style>
        table, td, th {
            border: 1px solid black;
        }

        th {
            background: yellowgreen;
        }
    </style>
<?php
echo '<code>';

$str = '-aąbcćdeęfghijklłmnńoópqrsśtuwvxyzżź';
$perLine = mb_strlen($str);

/*class bst
{

    public $left = NULL;
    public $right = NULL;
    public $value = false;

    public function __construct($value)
    {
        $this->value = $value;
    }

    public function insert($value)
    {
        var_dump($value);
    }
}*/

#$header = new bst('a');

$words = array();

$file = fopen('slowa-win.txt', 'r');
$lines = 0;
$totalLenght = 0;
while ($word = fgets($file)) {
    $word = str_replace("\r\n", '', $word);
    #echo $word . '<br/>' . PHP_EOL;

    $reference = & $words;

    $totalLenght += mb_strlen($word);
    for ($i = 0; $i < mb_strlen($word); $i++) {
        $letter = mb_substr($word, $i, 1);
        if (array_key_exists($letter, $reference)) {
            #echo 'F';
        } else {
            $reference[$letter] = array();
        }

        $reference = & $reference[$letter];
    }

    $lines++;
    /*if ($lines >= 500000) {
        break;
    }*/
}
fclose($file);

echo $word . '<br/>';

function tab($array, $level = 0)
{
    #echo '<br/>';
    $cnt = count($array);
    foreach ($array as $k => $v) {
        #echo str_repeat('_', $level * 1) . $k;
        if (is_array($v)) {
            $cnt += tab($v, $level + 1);
        }
    }
    return $cnt;
}

$totalSaved = tab($words);
echo $totalLenght . '<br/>';
echo $totalSaved . '<br/>';
echo round($totalSaved / $totalLenght * 100, 2) . '%<br/>';
echo round($totalLenght / $totalSaved, 2) . 'x<br/>';