C++ examples for Data Structure:Linked List
Summing and Averaging Elements in a linked List
#include <algorithm> #include <cstdlib> #include <ctime> #include <iostream> #include <vector> template <typename NODETYPE> class List;/*ww w.j a v a 2 s .c om*/ template <typename NODETYPE> class ListNode { friend class List<NODETYPE>; // make List a friend public: explicit ListNode(const NODETYPE &); NODETYPE getData() const; ListNode<NODETYPE>* next() const; private: NODETYPE data; ListNode<NODETYPE> *nextPtr; }; template <typename NODETYPE> ListNode<NODETYPE>::ListNode(const NODETYPE &info) : data(info), nextPtr(0) {} template <typename NODETYPE> NODETYPE ListNode<NODETYPE>::getData() const { return data; } template <typename NODETYPE> ListNode<NODETYPE>* ListNode<NODETYPE>::next() const { return nextPtr; } template <typename NODETYPE> class List { public: List(); ~List(); void insertAtFront(const NODETYPE &); void insertAtBack(const NODETYPE &); bool removeFromFront(NODETYPE &); bool removeFromBack(NODETYPE &); void concatenate(List<NODETYPE> &); bool isEmpty() const; void print() const; int size() const; ListNode<NODETYPE>* begin() { return firstPtr; } ListNode<NODETYPE>* end() { return lastPtr; } private: ListNode<NODETYPE> *firstPtr; // pointer to first node ListNode<NODETYPE> *lastPtr; // pointer to last node int sz; ListNode<NODETYPE> *getNewNode(const NODETYPE &); }; template <typename NODETYPE> List<NODETYPE>::List() : firstPtr(0), lastPtr(0), sz(0) {} template <typename NODETYPE> List<NODETYPE>::~List() { if (!isEmpty()) { ListNode<NODETYPE> *currentPtr = firstPtr; while (currentPtr != 0) { ListNode<NODETYPE> *tempPtr = currentPtr; currentPtr = currentPtr->nextPtr; delete tempPtr; } } } template <typename NODETYPE> void List<NODETYPE>::insertAtFront(const NODETYPE &value) { ListNode<NODETYPE> *newPtr = getNewNode(value); if (isEmpty()) { firstPtr = lastPtr = newPtr; // new list only has one node } else { newPtr->nextPtr = firstPtr; // point new node to previous list node firstPtr = newPtr; } ++sz; } template <typename NODETYPE> void List<NODETYPE>::insertAtBack(const NODETYPE &value) { ListNode<NODETYPE> *newPtr = getNewNode(value); if (isEmpty()) { firstPtr = lastPtr = newPtr; // new list has only one node } else { lastPtr->nextPtr = newPtr; lastPtr = newPtr; } ++sz; } template <typename NODETYPE> bool List<NODETYPE>::removeFromFront(NODETYPE &value) { if (isEmpty()) { // list is empty return false; } else { ListNode<NODETYPE> *tempPtr = firstPtr; if (firstPtr == lastPtr) firstPtr = lastPtr = 0; // no nodes remain after removal else firstPtr = firstPtr->nextPtr; // point to previous 2nd node value = tempPtr->data; delete tempPtr; --sz; return true; } } template <typename NODETYPE> bool List<NODETYPE>::removeFromBack(NODETYPE &value) { if (isEmpty()) { // list is empty return false; } else { ListNode<NODETYPE> *tempPtr = lastPtr; if (firstPtr == lastPtr) { // list has one element firstPtr = lastPtr = 0; // no nodes remain after removal } else { ListNode<NODETYPE> *currentPtr = firstPtr; // locate second to last element while (currentPtr->nextPtr != lastPtr) currentPtr = currentPtr->nextPtr; // move to next node lastPtr = currentPtr; // remove last node currentPtr->nextPtr = 0; // this is now the last node } value = tempPtr->data; delete tempPtr; --sz; return true; } } template <typename NODETYPE> void List<NODETYPE>::concatenate(List<NODETYPE> &listSecond) { ListNode<NODETYPE> *currentPtr = listSecond.firstPtr; while (currentPtr != 0) { insertAtBack(currentPtr->getData()); currentPtr = currentPtr->nextPtr; } } template <typename NODETYPE> bool List<NODETYPE>::isEmpty() const { return firstPtr == 0; } template <typename NODETYPE> ListNode<NODETYPE> *List<NODETYPE>::getNewNode(const NODETYPE &value) { return new ListNode<NODETYPE>(value); } template <typename NODETYPE> void List<NODETYPE>::print() const { if (isEmpty()) { std::cout << "The list is empty\n\n"; return; } ListNode<NODETYPE> *currentPtr = firstPtr; while (currentPtr != 0) { std::cout << currentPtr->getData() << ' '; currentPtr = currentPtr->nextPtr; } } template <typename NODETYPE> int List<NODETYPE>::size() const { return sz; } int main(int argc, const char* argv[]) { List<int> intList; std::vector<int> data; // for sorting the data const int RAND_LIMIT = 100; const int LIST_SIZE = 25; std::srand(std::time(0)); for (int i = 0; i < LIST_SIZE; ++i) { data.push_back((rand() % RAND_LIMIT)); } std::sort(data.begin(), data.end()); for (unsigned int i = 0; i < data.size(); ++i) { intList.insertAtBack(data[i]); } long sum = 0; ListNode<int>* iter = intList.begin(); do { sum += iter->getData(); iter = iter->next(); if (iter->getData() == intList.end()->getData()) sum += iter->getData(); } while (iter != intList.end()); std::cout << "sum: " << sum << " average: " << (sum / LIST_SIZE) << std::endl; intList.print(); std::cout << std::endl; return 0; }