Lecture04 - CMPSC 24 Lecture 4 Implemen8ng Linked Lists in...

Unformatted text preview: 4/6/10 CMPSC 24: Lecture 4 Implemen8ng Linked Lists in C++ Divyakant Agrawal Department of Computer Science UC Santa Barbara LINKED LISTS Linked List Using Pointers struct NodeType { int info; NodeType* next; }; NodeType* list; NodeType* loca8on; 3 1 4/6/10 Linked List Be sure you understand the differences among location, *location, and location->info loca8on ‐>info is the same as (*loca8on).info 4 Linked List Opera8ons Set list to empty Add a new node to list Count the number of nodes in list Remove the last node from list •  •  •  •  5 Structure Defini8on struct Node { int data; Node* next; Node (int item); Node (int item, Node* nextNode); } Node::Node(int item): data(item), next(0) { } Node::Node(int item, Node* nextNode): data(item), next(nextNode) { } 2 4/6/10 Declaring the Linked List Node* MyList; Finding an Element in the List bool find(int key) { bool found=false; Node* p = MyList; // traverse the list to find the item // DEVELOP THE CODE IN THE CLASS } Inser8ng an Element at the End of the list void insert(int key) { Node* newNode = new Node(key); // lets keep things simple // add to the end of the list // traverse the list to get to the last node in the list // What about boundary conditions? // DEVELOP THE CODE IN THE CLASS } 3 4/6/10 Dele8ng an Element from the list void delete(int key) { // traverse the list to find the node that matches “key” // we need to remove this node from the list // why is this more complex? // break down the complexity of the procedure into different cases // what are the different cases? // develop the implementation in class } Varia8on of the implementa8on •  Assuming that insert/append is the common case – can we make it more efficient? •  What if we need to insert an element in the middle? LINKED LISTS C++ CLASS: PUTTING IT TOGETHER 4 4/6/10 Example linkedlist.h #include <iostream> // compiler direc8ves using namespace std; // compile direc8ves Class linkedlist{ private: struct node{ int data; node *link; } *list; public: linkedlist(); // Constructor void append( int num ); // append a node with “num” void delete( int num ); // delete the node containing “num” bool find( int num ); // TRUE if “num” exists in the list ~linkledist(); // Destructor (to ensure no memory leak) }; Skeleton of linkedlist.cpp linkedlist::linkedlist() { p=NULL; } void linkedlist::append(int num) { // the code we developed goes in here . . } void linkedlist::delete(int num) { // the code we developed goes in here } Skeleton of linkedlist.cpp bool linkedlist::find(int num) { // the code we developed goes in here . . } Linkedlist::~linkedlist() { // ask the students what should happen here? . . } 5 4/6/10 Usage of linkedlist Class int main() { linkedlist myList; myList.append(35); myList.append(45); myList.append(37); if myList.find(36) cout<<“36 on the list????”<endl; else cout<<“36 not on the list!!!”<<endl; // you should get the idea… // would it be nice to have myList.display() ??? Lel as an exercise!!! } 6 ...
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