<?php
require_once 'inc/look_and_say.func.php';
// ridiculously high.
ini_set('memory_limit', '1G');
$result = trim(file_get_contents('input.txt'));
for ($i = 0; $i < 50; ++$i) {
$result = look_and_say($result);
}
$len = strlen($result);
echo "Answer: {$len}\n";
<?php
$input_str = '1321131112';
$turns_nr = 40;
echo '<pre>';
var_dump(look_and_say($input_str, $turns_nr));
echo '</pre>';
function look_and_say($str, $turns_nr)
{
for ($i = 0; $i < $turns_nr; $i++) {
$length = strlen($str);
$new_str = '';
$current_char_nr = 0;
$current_char = '';
for ($j = 0; $j < $length; $j++) {
$char = $str[$j];
if (empty($current_char) || $current_char != $char) {
if (!empty($current_char) && !empty($current_char_nr)) {
$new_str .= $current_char_nr . $current_char;
}
$current_char = $char;
$current_char_nr = 0;
}
$current_char_nr++;
$chars[$char] = true;
}
$new_str .= $current_char_nr . $current_char;
$str = $new_str;
}
return strlen($str);
}