function plagiarismCheck($code1, $code2)
{
    $c1 = implode(" ", $code1);
    $c2 = implode(" ", $code2);
    if ($c1 === $c2) {
        return false;
    }

    $d1 = $d2 = $rCand = [];

    preg_match_all('/[\w]+/', $c1, $d1);
    preg_match_all('/[\w]+/', $c2, $d2);

    foreach ($d1[0] as $k => $v) {
        if ($v !== $d2[0][$k] && ! is_numeric($v)) {
            $rCand[$v] = $d2[0][$k];
        }
    }

    foreach ($rCand as $orig => $repl) {
        $c1 = preg_replace("/(\W){$orig}(\W*)/", '$1PLACEHOLDER' . $orig . '$2', $c1);
        $c1 = preg_replace("/(\W){$orig}/", '$1PLACEHOLDER' . $orig, $c1);
    }

    foreach ($rCand as $orig => $repl) {
        $c1 = preg_replace("/(\W)PLACEHOLDER{$orig}(\W)/", '$1' . $repl . '$2', $c1);
        $c1 = preg_replace("/(\W)PLACEHOLDER{$orig}/", '$1' . $repl, $c1);
    }

    return $c1 === $c2;

}