跪求PHP字符串处理思路

怎么才能把形如以下字符串

12345
12456
12467
23456
23467
4
5

转换为

12
    (345)
    (4
        (56)(67)
    )
234
    (56)
    (67)
4
5

https://www.jb51.net/article/125238.htm
https://www.cnblogs.com/muziyun1992/p/6889280.html