I have addressed all your comments in my previous post. C++ implementation of a linked list
Can you please comment on,
- How efficient the code is?
- Am i using too much extra variables to implement each functionalities?
How can i improve error handling,return codes?
class LinkedList{ public: LinkedList(): head(nullptr), tail(nullptr){} ~LinkedList(){ Node *temp; while( head!=NULL ) { temp = head; head = head->next; delete temp; } tail = NULL; } /* copy constructor */ LinkedList(const LinkedList& new_item): head(nullptr), tail(nullptr){ Node *temp = new_item.head; Node *node; if(temp) head = node = new Node(); while(temp != NULL){ node->item = temp->item; if(temp->next) { node->next = new Node(); node = node->next; } else { tail = node; } temp = temp->next; } } void InsertFront(int key); /*Insert a node in head of the list*/ void InsertBack(int key); /*Insert a node in end of the list*/ int TopBack(); /*Get tail node - complexity-O(1) */ int TopFront(); /*Get head node - complexity-O(1) */ void PopBack(); /*Remove the first element in list.complexity-O(n)*/ void PopFront(); /*Remove the first element in list.complexity-O(1) */ void DeleteNode(int key); /*Delete first matching node of a given key.complexity-O(n)*/ void PrintList(std::ostream& out); private: struct Node { int item; Node *next; Node(): item(-1), next(nullptr) {} Node(int key): item(key), next(nullptr) {} }; Node *head; Node *tail; }; /*Insert a node in head of the list*/ void LinkedList::InsertFront(int key) { Node *node = new Node(key); if(!node) { std::cout << "ERR: Failed to allocate new node \n"; return; } if(head != NULL){ node->next = head; } else { tail = node; } head = node; } /*Insert a node in end of the list*/ void LinkedList::InsertBack(int key) { Node *node = new Node(key); if(!node) { std::cout << "ERR: Failed to allocate new node \n"; return; } if(!head) { head = node; } else { tail->next = node; } tail = node; } /*Get tail node - complexity-O(1) */ int LinkedList::TopBack(){ if(!tail) { std::cout << "ERR: List is empty\n"; return -1; } return tail->item; } /*Get head node - complexity-O(1) */ int LinkedList::TopFront(){ if(!head) { std::cout << "ERR: List is empty\n"; return -1; } return head->item; } /* Remove the first element in list. complexity-O(n) */ void LinkedList::PopBack(){ if(!tail){ std::cout << "ERR: List is empty to PopBack \n"; return; } if(head == tail) { std::cout << "popback item is - " << head->item << "\n"; delete head; head = tail = NULL; return; } Node *temp = head; while(temp->next!=tail) { temp = temp->next; } std::cout << "popback item is - " << tail->item << "\n"; delete tail; tail = temp; tail->next = NULL; return; } /* Remove the first element in list. complexity-O(1) */ void LinkedList::PopFront(){ if(!head){ std::cout << "ERR: List is empty to Popfront \n"; return; } if(head == tail) tail = NULL; std::cout << "popfront item is - " << head->item << "\n"; Node *temp = head; head = head->next; delete temp; return; } /*Delete first matching node of a given key*/ void LinkedList::DeleteNode(int key) { Node *node,*prev; node = head; while(node != NULL){ if(node->item == key) break; prev = node; node = node->next; } if(node == NULL) { std::cout << "Item not found in list \n"; return; } if(node == head){ if(node == tail){ std::cout << " Deleting Node with item " << node->item << " - only node available in list \n"; delete node; head = tail = NULL; return; } prev = head; head = head->next; std::cout << " Deleting Node with item " << prev->item << " - head node of list\n"; delete prev; return; } if(node == tail){ prev->next = NULL; std::cout << " Deleting Node with item " << tail->item << " - tail node of list\n"; delete tail; tail = prev; return; } prev->next = node->next; std::cout << " Deleting Node with item " << node->item << " - middle node of list\n"; delete node; return; } /*Print whole list*/ void LinkedList::PrintList(std::ostream& out) { Node *temp = head; while( temp != NULL ) { std::cout << temp->item << "\t"; temp = temp->next; } std::cout << "\n"; } /* Test code */ void testlist( LinkedList &new_list ){ new_list.InsertFront(10); new_list.PrintList(std::cout); new_list.InsertFront(50); new_list.PrintList(std::cout); new_list.InsertFront(20); new_list.PrintList(std::cout); new_list.InsertBack(60); new_list.PrintList(std::cout); } void insert_random_nos(LinkedList &new_list){ int i; for(i=133;i>11;i=i-7) { new_list.InsertFront(i%23); } } int main() { LinkedList new_list; new_list.InsertFront(70); testlist(new_list); insert_random_nos(new_list); LinkedList y(new_list); new_list.PrintList(std::cout); y.PrintList(std::cout); }
