[자료 구조] C++ Singly Linked List로 Stack 구현

#include <iostream>
using namespace std;

#define endl '\n'

struct Node {
    int val;
    Node* next;
};


class LinkedList {
public:
    LinkedList();
    int getSize() const;
    bool isEmpty() const;
    int getTop() const;
    void push(const int& _val);
    int pop();

private:
    Node* head;
    Node* tail;
    int size;
};

LinkedList::LinkedList() {
    head = nullptr;
    tail = nullptr;
    size = 0;
}

int LinkedList::getSize() const {
    return size;
}

bool LinkedList::isEmpty() const {
    if (size == 0)
        return 1;
    else
        return 0;
}

int LinkedList::getTop() const {
    if (isEmpty()) {
        return -1;
    }
    return head->val;
}

void LinkedList::push(const int& _val) {
    Node* newNode = new Node;
    newNode->val = _val;
    ++size;
    if (isEmpty()) {
        head = newNode;
        tail = newNode;
    }
    else {
        Node* tmp = head;
        head = newNode;
        head->next = tmp;
    }
}

int LinkedList::pop() {
    if (isEmpty()) {
        return -1;
    }
    Node* tmp = head->next;
    int result = head->val;
    delete head;
    head = tmp;
    --size;
    return result;
}


int main() {
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    int N;
    cin >> N;
    
    LinkedList* List = new LinkedList;

    string input;
    int val;
    for (int i = 0; i < N; ++i) {
        cin >> input;
        if (input == "size") {
            cout << List->getSize() << endl;
        }
        else if (input == "empty") {
            cout << List->isEmpty() << endl;
        }
        else if (input == "top") {
            cout << List->getTop() << endl;
        }
        else if (input == "push") {
            cin >> val;
            List->push(val);
        }
        else if (input == "pop") {
            cout << List->pop() << endl;
        }
    }

    return 0;
}