Question

assume that s is a stack and q1 and q2 are two queues which support the enqueue and dequeue operations. consider the following pseudo code for implementing the pop and push operation on s. [note: swap(x,y) exchanges the two queues x and y.] push(s,x) a(q2,x) while(q1 not empty) b(q2, c(q1)); swap(q1, q2) pop(s) return(d(q1)) which of the following options for the functions a, b, c, and d correspond to correctly implementing the push and pop operations on the stack s?

Answer 1

The provided pseudo code implements the push and pop operations on a stack using queues.

Step-by-step explanation:

The given pseudo code provides an implementation of the push and pop operations on a stack using two queues. Here is the explanation of each function:

• a(q2, x): This function enqueues the element x to the queue q2.
• b(q2, c(q1)): This function dequeues all the elements from queue q1 and enqueues them to queue q2.
• c(q1): This function dequeues and returns the front element of queue q1.
• d(q1): This function dequeues and returns the front element of queue q1. It is used in the pop(s) operation to retrieve the top element of the stack.

The correct implementation of push and pop operations on the stack s using the given functions would be:

• push(s, x): a(q2, x)
• pop(s): return(d(q1))