1. password syntax check. u get a string and need to make sure it has upper and lower characters and numbers and special characters and so on. solution with regex is easy. 2. u get a message and u need to crop it to be K characters, u cant cut in the middle of a word and dont cut spaces. example "something some here we are" K=17 will return "something some". 3. air plane arrange sits. u get a string that represnet the rows in an airplane some of those sits are taken and you need to sit families of 4 toghter as much as possible. can be solved with hashMaps or arrays or even DFS.
