题目：把字符串嵌套关系转换成数组,字符串只包含成对中括号、数字和逗号

字符串：(1,(1,2,(1,(1,2,(1)),3)),3,(1,(1,2,((1((1,(1,2,(1,2,3),4,5),3),2)),2)),((1,2,3),2,3),4,5),5)

程序：

$string = '(1,(1,2,(1,(1,2,(1)),3)),3,(1,(1,2,((1,((1,(1,2,(1,2,3),4,5),3),2)),2)),((1,2,3),2,3),4,5),5)';$result = $previous = [];$current = $number = null;$i = 0;while ( isset($string[$i]) ) {    $value = $string[$i];    switch ($value) {        case '(':            if ( is_null($current) ) {                $current = &$result;            } else {                $previous[] = &$current;                $current[] = [];                $current = &$current[count($current) - 1];            }            break;        case ')':            if ( !is_null($number) ) {                $current[] = intval($number);                $number = null;            }            $last = count($previous) - 1;            $current = &$previous[$last];            array_pop($previous);            break;        case ',':            if ( !is_null($number) ) {                $current[] = intval($number);                $number = null;            }            break;        default:            $number .= $value;            break;    }    $i++;}echo json_encode($result);

输出结果：[1,[1,2,[1,[1,2,[1]],3]],3,[1,[1,2,[[1,[[1,[1,2,[1,2,3],4,5],3],2]],2]],[[1,2,3],2,3],4,5],5]