LeetCode 420. Strong Password checker

Thoughts for [Case.3]
1. Delete first in [3+Row]s with minimizing [BR] case after Deleting in [3+Rows]
2. Don’t Delete all thing in one [3+Row] case to avoid to update [LUD] status.
3. You can delete from every position.
so Don’t try to delete from the start position and Don’t consider the position of [3+Rows] .

It was not easy for me because I didn’t a coding recently. and It took a long time to solve this problem. Anyway, All code and solutions were made by myself. I didn’t refer any others. I will upload a code after optimizing. (maybe 🙂 )

L1~L4 TCP/IP

I hope you are clear about How works Mac-address, IP-address, TCP/UDP-Port to Control TCP/IP sessions.

1) Mac address is only for devices that are directly physically connected.
All NICs will have different addresses by manufacturing.
Same MAC address on peers is not a problem to connect with other peers out of Physical Connection.

( it’s different with IP address working)

2) destination IP address is for choosing a network interface port(different from TCP/IP port.) in the network device.
All IP addresses must be unique on the internet. ( exp. IP anycasting and ..for controlling traffic tech.)

3) TCP/IP port is for delivering data to a proper application.
well known port: ~1024 (HTTP/80 and SSH/22 so on). you can check it from /etc/services (in a LINUX).