Implement_Queue.xpp

#include <bits/stdc++.h> 

struct Node {
    int val;
    Node * next;

    Node(int x) {
        val = x;
        next = NULL;
    }
};

class Queue {
    Node * head;
    Node * tail;
public:
    Queue() {
        // Implement the Constructor
        head = NULL;
        tail = NULL;
    }

    /*----------------- Public Functions of Queue -----------------*/

    bool isEmpty() {
        if(head == NULL) return true;
        return false;
    }

    void enqueue(int data) {
        Node * newNode = new Node(data);
        if(head == NULL) {
            head = newNode;
            tail = newNode;
            return;
        }
        tail->next = newNode;
        tail = newNode;
    }

    int dequeue() {
        if(head==NULL) return -1;
        int val = head->val;
        head = head->next;
        if(head == NULL) tail=NULL;
        return val;
    }

    int front() {
        if(head == NULL) return -1;
        return head->val;
    }
};