interview started with explain oops concept, polymorphism, encapsulation, call by value, call by reference different, get and post method, series 1,3,4,8,15,27,50 what is next number 2nd round 1.wirte a method with parameter() that will calculate total balls conditions : user will give the the nth of series calculate total number numbers of balls which is in series 2,1,2,1,2.....n