Linked list class in c++

A brief tutorial for linked list from the Stanford University.


Linked list at Youtube:


Tutorial: https://www.youtube.com/watch?v=U-MfAoL6qjM

Reverse a linked list

Detect a loop in a linked list

Find the junction node of two lists

Find the mid point of a list by just one scanning

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/****************************************************************************************** ******************************************************************************************* Chapter 2 Linked List: a class and three interview questions By: Hamed Kiani (July 25, 2015) ****************************************************************************************** ******************************************************************************************/ #include "stdafx.h" #include <iostream> #include <cstring> using namespace std; // a struct of linked list node, // contains two elements, _data: the value of node, _next: a pointer to the next node/NULL struct Node{ int _data; Node* _next; }; // LinkedList class, // private: // _head: keeps the head address (first node) // _tail: keeps the tail address (last node) // _size: the number of nodes in a linked list // public: // LinkedList(): constructor // ~LinkedList(): destructor // size(): return the _size of the list // addFront(data): add a node at begining/head of the list with _data = data // addTail(data): add a node at end/tail of the list with _data = data // deleteFront(): delete the first node of the list // deleteTail(): delete the tail node // getHead(): return the address of list's head // getTail(): return the address of list's tail // insertAfter(position, data): instert a node with data value after the position address // deleteThisNode(position): delete the node at the position address // searchInList(data): find data in the list // reverseList(): reverse the linked list // addWithList(listTemp): sum the list with the listTemp // appendTheList(listTemp): append the listTemp to the end of the list // printList(): print the list // printListRecursion(temp): recursion version of print list // remove_deuplicate_fun_1(): remove duplicate values in the list // nth_to_end_node(n): return the address of the n-th to end of the list // class declaration class LinkedList{ private: Node* _head; Node* _tail; int _size; public: LinkedList(); ~LinkedList(); int size(); void addFront(int data); void addTail(int data); void deleteFront(); void deleteTail(); Node* getHead(); Node* getTail(); void insertAfter(Node* position, int data); void deleteThisNode(Node* position); int searchInList(int data); void reverseList(); void addWithList(const LinkedList *listTemp); void appendTheList(const LinkedList *listTemp); void printList(); void printListRecursion(Node* temp); void remove_deuplicate_fun_1(); Node* nth_to_end_node(int n); }; LinkedList::LinkedList() { _head = NULL; _tail = NULL; _size = 0; } LinkedList::~LinkedList() { cout << "**********DESTRUCTOR***********" << endl; cout << "**********DESTRUCTOR***********" << endl; cout << "**********DESTRUCTOR***********" << endl; cout << "the destructor is called! deleting the linked list by calling deleteFront() function!" << endl; while (_size>0) deleteFront(); } int LinkedList::size() { return _size; } void LinkedList::addFront(int data) { Node* nodeTemp = new Node; if (_head == NULL) { nodeTemp->_data = data; _head = nodeTemp; _tail = nodeTemp; nodeTemp->_next = NULL; _size = 1; } else { nodeTemp->_data = data; nodeTemp->_next = _head; _head = nodeTemp; _size++; } cout << "the value: " << data << " is added to the front of list! " << "current size is: " << _size << endl; } void LinkedList::addTail(int data) { Node* nodeTemp = new Node; nodeTemp->_data = data; nodeTemp->_next = NULL; if (_tail != NULL) { _tail->_next = nodeTemp; _tail = nodeTemp; _size++; cout << "the value: " << data << " is added to the tail of list! " << "current size is: " << _size << endl; } else addFront(data); } void LinkedList::printList() { cout << "***********************************" << endl; cout << "The list containts: " << endl; int i = _size; Node* temp = _head; while (i>0) { cout << temp->_data << " " ; temp = temp->_next; i--; } cout << endl; cout << "***********************************" << endl; } void LinkedList::deleteFront() { if (_head == NULL) return; int data = _head->_data; Node* temp; temp = _head; if (_head->_next == NULL) { _head = NULL; _tail = NULL; } else _head = _head->_next; _size--; delete temp; cout << "the value: " << data << " is deleted from the front of list! " << "current size is: " << _size << endl; } void LinkedList::deleteTail() { if (_tail == NULL) return; int data = _tail->_data; Node* temp = _head; while (temp->_next != _tail) temp = temp->_next; _tail = temp; temp = temp->_next; _tail->_next = NULL; delete temp; _size--; cout << "the value: " << data << " is deleted from the tail of list! " << "current size is: " << _size << endl; } Node* LinkedList::getHead() { return _head; } Node* LinkedList::getTail() { return _tail; } void LinkedList::insertAfter(Node* position, int data) { if (position == NULL) { addFront(data); return; } if (position->_next == NULL) { addTail(data); return; } Node* temp = new Node; temp->_data = data; temp->_next = position->_next; position->_next = temp; _size++; } void LinkedList::deleteThisNode(Node* position) { if (position == NULL) return; if (position == _head) { deleteFront(); return; } if (position->_next == NULL) { deleteTail(); return; } Node * temp = _head; while (temp->_next != position) temp = temp->_next; temp->_next = position->_next; delete position; _size--; } int LinkedList::searchInList(int data) { Node* temp = _head; int i = 1; while (temp != NULL) { if (temp->_data == data) return i; temp = temp->_next; i++; } return -1; } void LinkedList::reverseList() { // keep the next node to add to reverse list. Node* next; // keep the head of the reversed list so far. // at the first, the reversed list is empty - null Node* prev = NULL; // a loop to traverse the list while (_head) { next = _head->_next; _head->_next = prev; prev = _head; _head = next; } // at the end, the head of reversed list is pointed by prev _head = prev; // we need to update the tail too next = _head; while (next->_next != NULL) next = next->_next; _tail = next; } void LinkedList::addWithList(const LinkedList *listTemp) { int s = listTemp->_size; if (s != _size) return; Node* t1 = listTemp->_head; Node* t2 = _head; while (t1 != NULL) { t2->_data += t1->_data; t1 = t1->_next; t2 = t2->_next; } } void LinkedList::appendTheList(const LinkedList *listTemp) { Node* temp = listTemp->_head; while (temp != NULL) { Node* newNode = new Node; newNode->_data = temp->_data; newNode->_next = NULL; _tail->_next = newNode; _tail = _tail->_next; temp = temp->_next; _size++; } } void LinkedList::printListRecursion(Node* temp) { if (temp == NULL) return; printListRecursion(temp->_next); cout << temp->_data << endl; } // inplace removing, O(n^2) time and O(1) additional space void LinkedList::remove_deuplicate_fun_1() { Node *head; Node *end; head = _head; int l = 0; if (!head) return; end = head->_next; Node *c; head = head->_next; while (head != NULL) { c = _head; while (c != end){ if (c->_data == head->_data) break; else c = c->_next; } if (c == end) { end->_data = head->_data; end = end->_next; } head = head->_next; } head = _head; while (head->_next != end) { l++; head = head->_next; _tail = head; } _size = ++l; head->_next = NULL; _tail->_next = NULL; } Node* LinkedList::nth_to_end_node(int n) { Node *p, *q; p = _head; q = _head; int i = 0; while (i < n & q != NULL) { q = q->_next; i++; } if (q == NULL) return NULL; while (q->_next != NULL) { q = q->_next; p = p->_next; } return p; } // some useful functions and linked list questions int pow(int a, int b) { if (b == 0) return 1; return a*pow(a, b - 1); } // time: O(N), additional space:O(N) void add_two_lists(LinkedList* l1, LinkedList* l2, LinkedList* l3) { if (!l1 & !l2) return; if (!l1) l3 = l2; if (!l2) l3 = l1; // convert the linked list to a decimal digit int d1 = 0; int d2 = 0; int i = 0; Node* temp1 = l1->getHead(); Node* temp2 = l2->getHead(); while (temp1 != NULL) { d1 += temp1->_data * pow(10, i); temp1 = temp1->_next; i++; } cout << "the digit of first link: " << d1 << endl; i = 0; while (temp2 != NULL) { d2 += temp2->_data * pow(10, i); temp2 = temp2->_next; i++; } cout << "the digit of 2nd link: " << d2 << endl; int add = d1 + d2; while ((add) > 0) { l3->addFront(add % 10); add /= 10; } } // without converting to decimal and re-digiting into the third linked list void add_two_lists_2(LinkedList* l1, LinkedList* l2, LinkedList* l3) { if (!l1 & !l2) return; if (!l1) l3 = l2; if (!l2) l3 = l1; int carry = 0; Node* temp1 = l1->getHead(); Node* temp2 = l2->getHead(); while (temp1 || temp2) { int t1 = (!temp1) ? 0 : temp1->_data; int t2 = (!temp2) ? 0 : temp2->_data; l3->addFront((t1 + t2 + carry) % 10); carry = (t1 + t2 + carry) / 10; if (temp1 != NULL) temp1 = temp1->_next; if (temp2 != NULL) temp2 = temp2->_next; } if (carry > 0) l3->addFront(1); } // find the joint node of two linked list: time O(N), memory: O(N) Node* find_joint_node_of_two_links(Node* h1, Node* h2) { if (!h1 | !h2) return NULL; int l1, l2; l1 = 0; l2 = 0; Node *temp = h1; while (temp != NULL) { l1++; temp = temp->_next; } temp = h2; while (temp != NULL) { l2++; temp = temp->_next; } int diff = (l1 - l2>0) ? (l1 - l2) : (l2 - l1); for (int i = 0; i < diff; i++) { if (l1 > l2) h1 = h1->_next; else h2 = h2->_next; } while (h1 != NULL & h2 != NULL){ if (h1 == h2) return h1; h1 = h1->_next; h2 = h2->_next; } return NULL; } // check if there is a loop in the linked list Node* is_loop_in_linkedlist(Node* head) { Node* slow = head; // moves one node Node* fast = head; // moves two nodes if (!head) return NULL; while (fast != NULL & fast->_next != NULL & slow != NULL) { slow = slow->_next; fast = fast->_next->_next; if (fast == slow) return slow; } return NULL; } // check the video and description in the post for more details Node* find_the_first_node_of_loop(Node* head) { Node* meetPoint = is_loop_in_linkedlist(head); if (meetPoint == NULL) return NULL; Node* temp; temp = head; while (temp != meetPoint) { temp = temp->_next; meetPoint = meetPoint->_next; } return temp; } void main() { // test the basics functions // a linked list object with five nodes LinkedList myList; myList.addFront(5); myList.addFront(4); myList.addFront(3); myList.addFront(2); myList.addFront(1); // print the list myList.printList(); // myList.printListRecursion(myList.getHead()); // add to the tail myList.addTail(1); myList.addTail(3); myList.addTail(3); // print the list myList.printList(); cout << "delete from front" << endl; myList.deleteFront(); myList.deleteTail(); myList.printList(); // print the head and tail values Node* tail = myList.getTail(); Node* head = myList.getHead(); cout << "the value in the first node is: " << head->_data << endl; cout << "the value in the last node is: " << tail->_data << endl; // insert a node in the list cout << "insert a new value of " << 200 << " in the third place: " << endl; Node* position = myList.getHead(); myList.insertAfter(position->_next, 200); myList.printList(); // delete a node from the list cout << "delete the third node: " << endl; position = myList.getHead(); myList.deleteThisNode(position->_next->_next); myList.printList(); // search a value in the linked list int pos = myList.searchInList(10); (pos < 0) ? (cout << "the value 10 is no found" << endl) : (cout << "the value 10 is found at node : " << pos << endl); // reverse the list myList.reverseList(); myList.printList(); // a new linked list object LinkedList myList_2; myList_2.addFront(7); myList_2.addFront(6); myList_2.addFront(5); myList_2.addFront(4); myList_2.addFront(4); myList_2.addFront(4); // adding the myList_2 to myList myList.addWithList(&myList_2); myList.printList(); // appending two lists myList.appendTheList(&myList_2); myList.printList(); // remove duplicates form myList myList.remove_deuplicate_fun_1(); myList.printList(); // return the n-th node to the end int n = 4; position = myList.nth_to_end_node(n); if (position) cout << " the " << n << " to end element is :" << position->_data << endl; else cout << "is longer the length of the list ! " << endl; // Problem1: adding the values of two linked lists LinkedList myList_3; add_two_lists(&myList, &myList_2, &myList_3); // add_two_lists_2(&myList, &myList_2, &myList_3); myList_3.printList(); // Problem 2: find the junction of two lists Node n1, n2, n3, n4, n5, n6; n1._data = 1; n2._data = 2; n3._data = 3; n4._data = 4; n5._data = 5; n6._data = 6; n1._next = &n2; n2._next = &n3; n3._next = &n4; n4._next = &n5; n5._next = NULL; n6._next = &n4; Node* conj = find_joint_node_of_two_links(&n1, &n6); if (!conj) cout << "there is no conjuction " << endl; else cout << "the conjuction node contains the value of : " << conj->_data << endl; // Problem 3: is there a cycle in the linked list n1._next = &n2; n2._next = &n3; n3._next = &n4; n4._next = &n5; n5._next = &n2; conj = is_loop_in_linkedlist(&n1); if (conj) cout << "there is a loop" << endl; else cout << "there is not loop" << endl; // Problem 4: if there is a cycle in the linked list, return the start node of the loop conj = find_the_first_node_of_loop(&n1); if (conj) cout << "the value of the start-loop node is : " << conj->_data << endl; else cout << "there is not loop" << endl; }