12. Explain the following stack member functions used in C++. (a) empty() (b) size() (c) pop() (d) stack() (e) push() (f) top() 13. What is a queue? Explain how a queue is simulated in STL. 14....

12. Explain the following stack member functions used in C++.

(a) empty() (b) size() (c) pop()

(d) stack() (e) push() (f) top()

13. What is a queue? Explain how a queue is simulated in STL.

14. Discuss the following queue member functions used in C++.

(a) back() (b) push() (c) empty()

(d) queue() (e) front() (f) size()

(g) pop()

15. Explain how a priority_queue class is realised in STL.