Cs212: DataStructures

Cs212: DataStructures Lab 6: Linked List (part 2)

Review • Common operations on a linked list: • Create a linked list. • Insert a node into the list. • Delete a node from the list. • Retrieve a node from the list.

Review (cont.) • Node Class classNode { // Declare Node class public: int Data; Node *next; // Pointer to next node Node(int d){ // constructor Data=d; next=NULL; } };

Review (cont.) • List Class class List{ // Declare List class private: Node *head; // pointer to the first Node in the list Node *tail;// pointer to the last Node in the list intcount; // count the number of nodes in the list public: List(){ // constructor count=0; head=tail=NULL; } intlistcount(){ // return the count of nodes in the list returncount; }

Review (cont.) • List Class – insertNode function voidInsertNode (intkey){ Node* NewNode = newNode(key); // create a new node if(count ==0){ // Is it empty list? head=tail=NewNode; count++;} else{ if( key < head->data){ // At beginning of the list NewNode->next= head; head=NewNode; count++;} else{ if(key > tail->data){ // at end of the list tail->next=NewNode; tail=NewNode; count++;} else{ Node* Ppre = NULL; // pointer to the previous node Node* PLoc = head; // pointer to the current node while( key > PLoc->data && PLoc->next != NULL ){ Ppre= PLoc; PLoc= PLoc->next;} if( key < PLoc->data ){ NewNode->next = PLoc; // or NewNode->next = Ppre->next; Ppre->next = NewNode; count++;} elsecout<< endl<<"Duplicated data ! "<< endl ; } } } }

Review (cont.) • List Class – displayList function voiddisplayList(){ // to print the data for each node in the list cout<<"List (first-->last):"<<endl; Node*current = head; while (current != NULL){ cout<< "{"<<current->data<< "} "; current = current->next; } cout<< endl; }

Delete a Node • Purpose: removes a node from linked list • Pre • key is identifier of node to be deleted • dataout is variable to receive a copy of the deleted data • Post • copied to output variable and node deleted or not found • Return • false if not found • true if deleted

Delete a Node (cont.) • List Class – DeleteNode function boolDeleteNode(int key , Node &dataout){ if (count == 0 || key < head->data || key > tail->data ) returnfalse; Node *pPre = NULL; Node *PLoc = head; while ( key != PLoc->data && PLoc->next != NULL ){ pPre = PLoc; PLoc = PLoc->next; } if ( PLoc->next == NULL && key != PLoc->data ) // the node does not exist in the list returnfalse; else{ if ( key == head->data ){ // At beginning of the list head = head->next; dataout.data=PLoc->data;} else{ if ( key == PLoc->data){ pPre->next=PLoc->next; dataout.data=PLoc->data;} } if ( PLoc->next == NULL ) tail = pPre; count--; deletePLoc;//freed memory returntrue; } }

Retrieve a Node • Purpose: Interface to search function • Pre • key is the search argument • dataOut is variable to receive data • Post • dataOut contains located data if found • if not found, contents are unchanged • Return • true if successful, false if not found

Retrieve a Node (cont.) • List Class – RetrieveNode function boolRetrieveNode( inttarget , Node& dataout){ if(count == 0 || target < head->data || target > tail->data ) returnfalse; Node*pPre = NULL; Node*pLoc = head; while(target != pLoc->data && pLoc->next != NULL){ pPre= pLoc; pLoc= pLoc->next; } if(target == pLoc->data){ dataout.data= pLoc->data; returntrue; } else returnfalse; } }; // end of the list class

Example 1 (cont.) • Main function #include<iostream> usingnamespacestd; voidmain() { //Using List List s; s.InsertNode(50); s.InsertNode(20); s.InsertNode(80); s.InsertNode(10); s.InsertNode(80); s.InsertNode(90); s.displayList(); cout<< " \n The number of nodes in the list is :" << s.listcount()<< "\n"; Noded(0); s.DeleteNode(80, d); cout<< d.data<<endl; d.data=0; s.DeleteNode(30, d); cout<< d.data<<endl; d.data=0; s.DeleteNode(10, d); cout<< d.data<<endl;d.data=0; s.displayList(); s.RetrieveNode(20, d) ; cout<< d.data<<endl;d.data=0; s.RetrieveNode(100, d) ; cout<< d.data<<endl; d.data=0; s.RetrieveNode(50, d) ; cout<< d.data<<endl; d.data=0; s.displayList(); system("pause"); }

Example 1 (cont.) • Output

Cs212: DataStructures