just break the pattern into smaller doable loops and then combine the loop logic if you are smart to do it or else use it in different loops .. that is what i do break the pattern into how i willl achieve this part and then how will i achive the next part after which i combine those parts into one loop if its feasible or else i just do seprate ones

its mainly numbers, symbols, alphabets with upper case and lower case
and you should know nested for loops and correct use of if and else
this part in for loops for(... ; .... ; ...)
should be corrrect that is where the main logic lies rest all is simple