Online PHP editor | refs for 9I40K

<?php function gray_code($bits) { if ($bits == 1) { return array('0', '1'); } else { $codes = gray_code($bits - 1); return array_merge(array_map(function ($v) { return '0' . $v; }, $codes), array_map(function ($v) { return '1' . $v; }, array_reverse($codes)) ); } } $value = 115; $bin = decbin($value); // get sufficient gray codes to cover the input $gray_codes = gray_code(strlen($bin)); $codes = array_flip($gray_codes); echo "$bin takes {$codes[$bin]} steps to reduce to 0\n"; // echo the steps for ($i = $codes[$bin]; $i >= 0; $i--) { echo $gray_codes[$i] . PHP_EOL; }