paper - scissor - rock

<?php
define('PSR_LOSE',		0x00000000);
define('PSR_DRAW',		0x00000001);
define('PSR_WIN',		0x00000002);  
define('PSR_PAPER',		0x00000000);
define('PSR_SCISSOR',	0x00000001);
define('PSR_ROCK',		0x00000002);

if(isset($_GET['psr']) && ctype_digit((string) $_GET['psr'])){
	
	$matrix=array(
			PSR_PAPER	=>	array(
									PSR_DRAW,
									PSR_LOSE,
									PSR_WIN
							),
			PSR_SCISSOR	=>	array(
									PSR_WIN,
									PSR_DRAW,
									PSR_LOSE
							),
			PSR_ROCK	=>	array(
									PSR_LOSE,
									PSR_WIN,
									PSR_DRAW
							)
	);
	$count		= count($matrix, COUNT_NORMAL);
	$recursive	= count($matrix, COUNT_RECURSIVE);
	//corrected:
	if($count % ($recursive - $count) == $count){
	//if(($recursive - $count) % $count == $count){
	//if(($recursive - $count) % ($recursive - $count) == 0){
		if($_GET['psr'] > $count xor  $_GET['psr'] < 0){
			echo 'cheater!<br/>'.PHP_EOL;
			exit;
		}
		else{
			$self     = rand(0,2);
			$result = $matrix[$_GET['psr']][$self];
			$string = '';
			
			switch($result){
				case PSR_LOSE	: $string .= 'You lose! ';	break;
				case PSR_DRAW	: $string .= 'Draw... ';	break;
				case PSR_WIN	: $string .= 'You won!!! ';	break;
			}
			switch($_GET['psr']){
				case PSR_PAPER	: $string .= 'Paper ';		break;
				case PSR_SCISSOR: $string .= 'Scissor ';	break;
				case PSR_ROCK	: $string .= 'Rock ';		break;
			}
			$string .= '  v.s.  ';
			switch($self){
				case PSR_PAPER		: $string .= 'Paper ';	break;
				case PSR_SCISSOR	: $string .= 'Scissor ';break;
				case PSR_ROCK		: $string .= 'Rock ';	break;
			}
			$string .= '<br/>'.PHP_EOL;
			echo $string;
			echo 'Wanna try again?<br/>'.PHP_EOL;
		}
	}
}
echo 'Pick your item: <br/>'.PHP_EOL;
echo '<a href="'.basename(__FILE__).'?psr='.PSR_PAPER.'">Paper</a><br/>'.PHP_EOL;
echo '<a href="'.basename(__FILE__).'?psr='.PSR_SCISSOR.'">Scissor</a><br/>'.PHP_EOL;
echo '<a href="'.basename(__FILE__).'?psr='.PSR_ROCK.'">Rock</a><br/>'.PHP_EOL;
?>