Consider the queues Q₁ containing four elements and Q₂ containing none (shown as the Initial State in the figure). The only operations allowed on these two queues are Enqueue (Q, element) and Dequeue (Q). The minimum number of Enqueue operations on Q₁ required to place the elements of Q₁ in Q₂ in reverse order (shown as the Final State in the figure) without using any additional storage is ______________.

A queue is implemented using an array such that ENQUEUE and DEQUEUE operations are performed efficiently. Which one of the following statements is CORRECT ($$n$$ refers to the number of items in the queue)?

The result evaluating the postfix expression $$10\,\,5\, + 60$$ $$\,\,6/\, * \,8\, - $$ is

A function f defined on stacks of integers satisfies the following properties. f(∅) = 0 and f (push (S, i)) = max (f(S), 0) + i for all stacks S and integers i. If a stack S contains the integers 2, -3, 2, -1, 2 in order from bottom to top, what is f(S)?