leetcode686. 重复叠加字符串匹配

function repeatedStringMatch(string $a, string $b) :int {
    $aLength = strlen($a);
    $bLength = strlen($b);

    for ($i = 0; $i < $aLength; $i++) {
        for ($j = 0; $j < $bLength && $a[($i + $j) % $aLength] == $b[$j]; $j++);

        if ($j == $bLength) {
            return intdiv($i + $j - 1, $aLength) + 1;
        }
    }

    return -1;
}