Problem 1. string "text" and string set "s2". Find a list of most frequent words from "text" and they are not in s2.
Rule:
When multiple words having same top frequency, return them all;
Case in-sensitive;
Special sign and number treated as space.
Trick, if you want to get full tests passed. Be aware of "text" edge cases. Like, empty, case. Same applied to "s2".

Problem 2. Logs sorting. Logs come with identifier. Logs content has two types, string one and digit one. Sort these logs come with string ones first, then digit ones. For string logs, sort by string initial, or sort by identifer if initial same.
Basically same as: https://leetcode.com/problems/reorder-data-in-log-files/solution/

That's it. And I hope it can help the community. Best luck for everyone!