Naive code gen

naive_code_gen.php

<?php

$len = 4;
$rand_fun = 'mt_rand';

$usedCodes = array();
$found = 0;
$max = pow(10, $len);
$prevSteps = 0;
$steps = 0;

$stats = array();
while ($found<$max) {
	$steps++;
	$code = gen_random($len);
	if (!in_array($code, $usedCodes)) {
		if ($found==0) {
			$stats[] = 1;
		} else {
			$stats[] = $steps-$prevSteps;
		}

		$prevSteps = $steps;
		$found++;
		$usedCodes[] = $code;

		/*if ($found%100==0) {
			mt_srand(microtime(true));
		}*/
	}	
}

echo "Code length: $len\n";
echo "Used random: $rand_fun()\n";
echo "Found: $found\n";
echo "Steps: $steps\n";
echo "Steps per found: ".($steps/$found)."\n";
echo "Max steps: ".call_user_func_array('max', $stats)."\n";

foreach (array_chunk($stats, sizeof($stats)/10) as $i=>$chunk) {
	echo "Range ".($i*10)."% - ".(($i+1)*10)."%: ".(array_sum($chunk)/sizeof($chunk))." steps on average, max: ".call_user_func_array('max', $chunk)."\n";
}

function gen_random($len=4) {
	global $rand_fun;

	$alphabet = array('1', '2', '3', '4', '5', '6', '7', '8', '9', '0');
	
	$code = '';
	for ($i=0; $i<$len; $i++) {
		$code .= $alphabet[call_user_func($rand_fun,0,9)];
	}
	
	return $code;
}