HA17

coloriot

Jul 25th, 2024

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C++ 3.90 KB | None | 0 0

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#include <iostream>
class List {
private:
class Node {
public:
Node(int val) : value(val), next(nullptr), prev(nullptr) {}
int value;
Node* next;
Node* prev;
};
Node* start;
Node* finish;
int size;
public:
List() : start(nullptr), finish(nullptr), size(0) {}
List(const List& other) : start(nullptr), finish(nullptr), size(0) {
Node* current = other.start;
while (current) {
push_back(current->value);
current = current->next;
}
}
~List() {
while (size > 0) {
pop_front();
}
}
// Оператор =, сделан из кода конструктора и деструктора
void operator = (const List& other) {
if (this == &other) {
return;
}
while (size > 0) {
pop_front();
}
Node* current = other.start;
while (current) {
push_back(current->value);
current = current->next;
}
}
void push_back(int new_value) {
Node* new_node = new Node(new_value);
if (size > 0) {
finish->next = new_node;
new_node->prev = finish;
} else {
start = new_node;
}
finish = new_node;
++size;
}
void push_front(int new_value) {
Node* new_node = new Node(new_value);
new_node->next = start;
if (start != nullptr) {
start->prev = new_node;
}
start = new_node;
if (size == 0) {
finish = new_node;
}
++size;
}
void pop_front() {
if (size == 0) {
return;
}
Node* old_start = start;
start = start->next;
if (start != nullptr) {
start->prev = nullptr;
} else {
finish = nullptr;
}
delete old_start;
--size;
}
void pop_back() {
if (size == 0) {
return;
}
Node* old_finish = finish;
finish = finish->prev;
if (finish != nullptr) {
finish->next = nullptr;
} else {
start = nullptr;
}
delete old_finish;
--size;
}
Node* getStart() const { return start; }
int getSize() const { return size; }
// Вот здесь я помучался, но нужно именно для этого класса, не для List
friend std::istream& operator >> (std::istream& in, List& list) {
int num_elements, value;
in >> num_elements;
for (int i = 0; i < num_elements; ++i) {
in >> value;
list.push_back(value);
}
return in;
}
friend std::ostream& operator << (std::ostream& out, const List& list) {
for (List::Node* current = list.start; current != nullptr; current = current->next) {
out << current->value << " "; // Чисто косметическое;
}
return out;
}
};
int main() {
List list;
std::cout << "Введите количество элементов и сами элементы: ";
std::cin >> list;
List copied_list(list);
int n, m;
std::cout << "push front: ";
std::cin >> n;
list.push_front(n);
std::cout << "push back: ";
std::cin >> m;
list.push_back(m);
std::cout << "pop front" << std::endl;
list.pop_front();
std::cout << "pop back" << std::endl;
list.pop_back();
List another_copied_list(list);
std::cout << "Оригинальный список: " << copied_list << std::endl;
std::cout << "Список: " << list << std::endl;
std::cout << "Еще один список: " << another_copied_list << std::endl;
return 0;
}

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