Queue

Problem Statement:
        Implement Queue

Solution: 

Given below is the kind of scenario in case of Queue Data structure ,
where items are pushed(en-queue-d) from rear and removed (de-queue-d) from front.

Fig: Example of Queue

Operations supported by Queue data structure are:
1. En-queue:
            It means insertion of elements from rear pointer
2. De-queue:
         It means deletion of items from front pointer.

A Queue supports FIFO operations i.e. First In First Out (FIFO)

Implementation:

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- /**  * Queue Implementation  * @author Prateek  */ public class Queue {     private static int DEFAULT_CAPACITY = 5;     int front;  int rear;  int arr[];    public Queue() {   arr = new int[DEFAULT_CAPACITY];   Arrays.fill(arr, -1);   front = 0;   rear = 0;  }    public Queue(int size) {   DEFAULT_CAPACITY=size;   arr = new int[DEFAULT_CAPACITY];   Arrays.fill(arr, -1);   front = 0;   rear = 0;  }     public void push(int data) {   rear = (rear) % (DEFAULT_CAPACITY);   if (arr[rear] == -1) {    arr[++rear] = data;    System.out.println("Pushed: " + arr[rear - 1]);   } else    System.out.println("Queue is Full");  }    public void pop() {   int val = arr[front];   arr[front] = -1;   front++;   System.err.println("Poped: " + val);  }    public void display() {   System.out.print("Queue is : \t");   int i = front;   while (i <= DEFAULT_CAPACITY) {    System.out.print(arr[i]+"\t");    i = (i + 1) % DEFAULT_CAPACITY;    if (i == rear)     break;   }  } } -

References:
http://basicstodatastructures.blogspot.in/2013/10/queue.html from a good friend of mine.

Please post your comments and suggestions

Happy Coding!! :)