Merge pull request #35 from ShehaniHettiarachchi/DataStructure

ThusharaX · web-flow · commit 040a62cb5d87 · 2022-10-23T00:05:05.000+05:30
Queue dataStructure
diff --git a/Basics/Data Structure/Queue-datastructure/QueueX.java b/Basics/Data Structure/Queue-datastructure/QueueX.java
@@ -0,0 +1,110 @@
+package Task1;
+
+public class QueueX {
+	private int[] arr;      // array to store queue elements
+    private int front;      // front points to the front element in the queue
+    private int rear;       // rear points to the last element in the queue
+    private int capacity;   // maximum capacity of the queue
+    private int count;      // current size of the queue
+ 
+    // Constructor to initialize a queue
+    QueueX(int size)
+    {
+        arr = new int[size];
+        capacity = size;
+        front = 0;
+        rear = -1;
+        count = 0;
+    }
+ 
+    // Utility function to dequeue the front element
+    public int dequeue()
+    {
+        // check for queue underflow
+        if (isEmpty())
+        {
+            System.out.println("Underflow\nProgram Terminated");
+            System.exit(-1);
+        }
+ 
+        int x = arr[front];
+ 
+        System.out.println("Removing " + x);
+ 
+        front = (front + 1) % capacity;
+        count--;
+ 
+        return x;
+    }
+ 
+    // Utility function to add an item to the queue
+    public void enqueue(int item)
+    {
+        // check for queue overflow
+        if (isFull())
+        {
+            System.out.println("Overflow\nProgram Terminated");
+            System.exit(-1);
+        }
+ 
+        System.out.println("Inserting " + item);
+ 
+        rear = (rear + 1) % capacity;
+        arr[rear] = item;
+        count++;
+    }
+ 
+    // Utility function to return the front element of the queue
+    public int peek()
+    {
+        if (isEmpty())
+        {
+            System.out.println("Underflow\nProgram Terminated");
+            System.exit(-1);
+        }
+        return arr[front];
+    }
+ 
+    // Utility function to return the size of the queue
+    public int size() {
+        return count;
+    }
+ 
+    // Utility function to check if the queue is empty or not
+    public boolean isEmpty() {
+        return (size() == 0);
+    }
+ 
+    // Utility function to check if the queue is full or not
+    public boolean isFull() {
+        return (size() == capacity);
+    }
+
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+		// create a queue of capacity 5
+        QueueX q = new QueueX(5);
+ 
+        q.enqueue(1);
+        q.enqueue(2);
+        q.enqueue(3);
+ 
+        System.out.println("The front element is " + q.peek());
+        q.dequeue();
+        System.out.println("The front element is " + q.peek());
+ 
+        System.out.println("The queue size is " + q.size());
+ 
+        q.dequeue();
+        q.dequeue();
+ 
+        if (q.isEmpty()) {
+            System.out.println("The queue is empty");
+        }
+        else {
+            System.out.println("The queue is not empty");
+        }
+
+	}
+
+}
