A circular linked list is one in which the next field for the last link node of the list points to the first link node of the list. This can be useful when you wish to have a relative positioning for elements, but no concept of an absolute first or last position.

Question

(a) Modify the code to implement circular singly linked lists.
// Linked list implementation
template <typename E> class LList: public List<E> {
private:
Link<E>* head; // Pointer to list header
Link<E>* tail; // Pointer to last element
Link<E>* curr; // Access to current element
int cnt; // Size of list
void init() { // Intialization helper method
curr = tail = head = new Link<E>;
cnt = 0;} void removeall() { // Return link nodes to free store
while(head != NULL) {
curr = head;
head = head->next;
delete curr;}}
public:
LList(int size=defaultSize) { init(); } // Constructor
˜LList() { removeall(); } // Destructor
void print() const; // Print list contents
void clear() { removeall(); init(); } // Clear list
// Insert "it" at current position
void insert(const E& it) {
curr->next = new Link<E>(it, curr->next);
if (tail == curr) tail = curr->next; // New tail
cnt++;}
void append(const E& it) { // Append "it" to list
tail = tail->next = new Link<E>(it, NULL);
cnt++;}
// Remove and return current element
E remove() {
Assert(curr->next != NULL, "No element");
E it = curr->next->element; // Remember value
ink<E>* ltemp = curr->next; // Remember link node
if (tail == curr->next) tail = curr; // Reset tail
curr->next = curr->next->next; // Remove from list
delete ltemp; // Reclaim space
cnt--; // Decrement the count
return it;}