I have a set of x string items e.g("A","B","C","D","E","F")
I need to know the formula that calculates how many combinations of n items and what is the
algorithm that generates all possible combinations
e.g
if we need to select 4 items from the list randomly.
those 4 items could be:
("A","B","C","D") or
("A","B","C","E") or
…