package com.learnds;

class Node{

int data;

Node next;

}

class Queue{

Node front ;//front(or head or top)

Node rear ;//rear(tail or last)

int capacity;

int currSize;

Queue(int capacity){

this.capacity = capacity;

front=rear=null;

}

void print(){

Node temp=front;

System.out.print("Queue contains : ");

while(temp!=null){

System.out.print(temp.data+"->");temp=temp.next;

}

System.out.println("NULL");

}

int getCurrSize(){

int count=0;

if(rear==null){

return count;

}

else{

Node temp=front;//queue starts from FRONT dont put REAR which will always return 1 REAR is TAIL of QUEUE

while(temp!=null){

count++;temp=temp.next;

}

return count;

}

}

boolean isQueueFull(){

return (getCurrSize() >= this.capacity);

}

boolean isQueueEmpty(){

return (getCurrSize() < 1 );

}

void peek() {

System.out.println("The front of queue is: "+ front.data);

}

void enqueue(int num){//insert or add or push

if(isQueueFull()){

System.out.println("Queue is full");

return;

}

if(rear == null){

rear = new Node();

rear.data = num;

rear.next = null;

front=rear;

}

else{

Node temp=new Node();

temp.data=num;

temp.next=null;

rear.next=temp;

rear=temp;

}

}

void dequeue(){//pop or remove or delete

if(isQueueEmpty()){

System.out.println("Queue is empty");

return;

}

Node temp=front;

front=temp.next;

System.out.println("Deleted "+temp.data);

//delete temp;

}

}

class QueueImplUsingList{

public static void main(String ar[]){

Queue q = new Queue(5);

q.enqueue(1);

q.enqueue(2);

q.enqueue(3);

q.enqueue(4);

q.enqueue(5);

q.enqueue(6);

q.peek();

q.print();

q.dequeue();

q.peek();

q.dequeue();

q.peek();

q.dequeue();

q.enqueue(7);

q.peek();

q.print();

}

}