Game of flipping identical cards

This is still no question, despite the question mark. Don't remove "NoEffort" "GimmeCode" and "Homework" tags. They are there for good: you want that somebody solves a task for you, bout you don't want do anything for it.

There are several methods to do that, the problem itself was given to you as homework related to some learning objectives, based on some literature or classroom session. So be brave, and do your homework yourself.