백준 온라인 저지(Baekjoon Online Judge) - 18258 : 큐 2

https://www.acmicpc.net/problem/18258

18258번: 큐 2

 

#include <iostream>
using namespace std;

struct Node {
    int data;
    Node* next;
    Node(int data) : data(data), next(NULL) {}
};

class Queue {
private:
    Node* front;
    Node* rear;
    int qSize;
public:
    Queue() : front(NULL), rear(NULL), qSize(0) {}
    ~Queue() {
        while (!isEmpty()) {
            pop();
        }
    }
    bool isEmpty() {
        return qSize == 0;
    }
    void push(int data) {
        Node* newNode = new Node(data);
        if (isEmpty()) {
            front = rear = newNode;
        } else {
            rear->next = newNode;
            rear = newNode;
        }
        qSize++;
    }
    int pop() {
        if (isEmpty()) {
            return -1;
        }
        Node* temp = front;
        int ret = temp->data;
        front = front->next;
        delete temp;
        qSize--;
        if (isEmpty()) {
            rear = NULL;
        }
        return ret;
    }
    int getSize() {
        return qSize;
    }
    int getFront() {
        if (isEmpty()) {
            return -1;
        }
        return front->data;
    }
    int getRear() {
        if (isEmpty()) {
            return -1;
        }
        return rear->data;
    }
};

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);

    int n, data;
    string cmd;
    Queue q;
    cin >> n;
    while (n--) {
        cin >> cmd;
        if (cmd == "push") {
            cin >> data;
            q.push(data);
        } else if (cmd == "pop") {
            cout << q.pop() << '\n';
        } else if (cmd == "size") {
            cout << q.getSize() << '\n';
        } else if (cmd == "empty") {
            cout << q.isEmpty() << '\n';
        } else if (cmd == "front") {
            cout << q.getFront() << '\n';
        } else if (cmd == "back") {
            cout << q.getRear() << '\n';
        }
    }

    return 0;
}