4. Queue is a FIFO (first in, first out) data structure, and it can be implemented using an array or a linked list. The variable "rear is often used to represent position where elements are added, and the variable "front is often used to represent the position from which elements are removed. Please answer the following questions. Dynamic queue is a type of queue, and it is often implemented using a linked list. Dynamic queue allows dynamic sizing and it avoids issue of wrapping indices. Below is the definition and initialization of the node for the linked list. - H +NULL . NULL front rear struct QNode char value; QNode *next; QNode(char ch, QNode *p = NULL) {value = ch; next = p;} QNode *front = NULL; QNode *rear = NULL; (i) Please write the code for checking if the queue is empty. (ii) Please write the code for adding an item to the queue