cpa_lab_5_3_13_(2)-B.cpp

#include <iostream>

using namespace std;

class Node
{
    public:
        Node(int val);
        int value;
        ~Node();
        Node* next;
};

Node::Node(int val) : value(val), next(nullptr)
{
	cout << "+Node" << endl;
}

Node::~Node()
{
	cout << "-Node" << endl;
}

class List
{
    public:
        List();
        ~List();
        void push_front(int value);
        bool pop_front(int value);
    private:
        Node* head;
};

List::List() : head(nullptr) { }

List::~List() {
	Node *t = head, *next;
	while (t != nullptr)
	{
		next = t->next;
		delete t;
		t = next;
	}
}

void List::push_front(int value)
{
	Node* new_head = new Node(value);
	new_head->next = head;
	head = new_head;
}

bool List::pop_front(int value)
{
	Node *t = head, *prev = nullptr;

	while (t != nullptr) {
		if (t->value == value) {
			if (prev == nullptr) {
				prev = head;
				head = head->next;
				delete prev;
			}
			else
			{
				prev->next = t->next;
				delete t;
			}
			return true;
		}
		else
		{
			prev = t;
			t = t->next;
		}
	}
	return false;
}

int main()
{
	List list;

	list.push_front(1);
	list.push_front(2);
	list.push_front(3);
	list.push_front(4);

	return 0;
}