Data Structures, Algorithms, & Applications in C++
Chapter 9, Exercise 13

(a)

The extensions are

input( ):

Input a queue from front to rear;

toString( ):

Return the queue elements, as a string, from front to rear;

split(a, b):

Split a queue into the queues a and b. The elements are distributed alternately to a and b, beginning with a.

combine(a, b):

Combine the queues a and b into a single queue. The elements in the combined queue are taken alternately from a and b, beginning with a.