PHP Weighted Random Choice & Selection Remove / Replacement

For something I have been doing in a php project of late, I needed to weight an array of values and as I go round and select the values remove the value or -1 from the weight depending on how many of the value are left in the weight.

If you have any improvements or suggestions then id very much like to here them icon smile PHP Weighted Random Choice & Selection Remove / Replacement

$starttime = microtime();
$startarray = explode(" ", $starttime);
$starttime = $startarray[1] + $startarray[0];
/**
 * weighted_random()
 * Pick a random item based on weights.
 *
 * @param array $values Array of elements to choose from
 * @param array $weights An array of weights. Weight must be a positive number.
 * @return mixed Selected element.
 */
	function weighted_random($values, $weights){
	    $count = count($values);
	    $i = 0;
	    $n = 0;
	    $num = mt_rand(0, array_sum($weights));
	    while($i < $count){
	        $n += $weights[$i];
	        if($n >= $num){
	            break;
	        }
	        $i++;
	    }
	    return $i;
	}
	function recalc($val,$values,$weight){
		//two steps to consider here, -1 from the weight and if the weight is <=0 unset both the value and the weight.
		if($weight[$val]-1<=0){
			unset($weight[$val]);
			unset($values[$val]);
			$new_values = array();
			$new_weight = array();
			foreach($values as $k=>$v){
				$new_values[]=$v;
				$new_weight[]=$weight[$k];
			}
			return array($new_values,$new_weight);
		}else{
			$weight[$val]=$weight[$val]-1;
			return array($values,$weight);
		}
	}
	//in the context of what im doing lets get this right.
	$values = array(0=>"164-2",1=>"164-1",2=>"2-2");
	$weights = array(0=>1,1=>2,2=>1);
	//now we wanna select 4 values but edit them as we go round.
	$find = 3;
	for($i=0;$i<$find;$i++){
		$val = weighted_random($values,$weights);
		echo $val.'  |  ';
		echo $values[$val].'
';
		list($values,$weights) = recalc($val,$values,$weights);
	}
	echo 'The new weights are ';
	print_r($weights);
	echo '
';
	$endtime = microtime();
	$endarray = explode(" ", $endtime);
	$endtime = $endarray[1] + $endarray[0];
	$totaltime = $endtime - $starttime;
	$totaltime = $totaltime;
	echo "This page loaded in $totaltime seconds.";
?>