Merge pull request tarunsinghofficial#1797 from Aryanshaw/main

Queue implementation in java

Java_Programs_for_beginners/Queue/Deque.java

@@ -0,0 +1,16 @@
+package Ds.Queue;
+import java.util.*;
+public class Deque {
+
+	public static void main(String[] args) {
+		ArrayDeque<Integer> dq = new ArrayDeque();
+	    dq.addFirst(12);
+	    dq.addFirst(23);
+	    dq.addFirst(42);
+	    dq.pop();
+
+	    System.out.println(dq.peek());
+
+	}
+
+}

Java_Programs_for_beginners/Queue/Runner.java

@@ -0,0 +1,20 @@
+package Ds.Queue;
+
+public class Runner {
+
+	public static void main(String[] args) {
+		arrayQueue q = new arrayQueue();
+		q.enQueue(5);
+		q.enQueue(4);
+		q.enQueue(3);
+		q.enQueue(7);
+		q.enQueue(6);
+		q.enQueue(1);
+//		q.enQueue(0);
+
+		q.deQueue();
+		q.show();
+		System.out.println("size is "+ q.getSize());
+	}
+
+}

Java_Programs_for_beginners/Queue/arrayQueue.java

@@ -0,0 +1,50 @@
+package Ds.Queue;
+
+public class arrayQueue {
+
+	int queue[] = new int [5];
+	int size;
+	int front;
+	int back;
+
+	public void enQueue(int data) {
+		if(!isFull()) {
+		queue[back] = data;
+		back = (back +1)%5;
+		size++;
+		}else {
+			System.out.println("Queue is full"); 
+		}
+	}
+	public int deQueue() {
+		int data = queue[front];
+		if(isEmpty()) {
+		    front= (front + 1)%5;
+		    size--;
+		}else {
+			System.out.println("queue is empty");
+		}
+		return data;
+	}
+
+	public void show() {
+		System.out.println("The number of elements are: ");
+		for(int i=0; i < size; i++) {
+			System.out.println(queue[(front+ i)%5]+ " ");
+		} 
+	}
+	public int getSize() {	
+		return size;
+	}
+	public boolean isEmpty() {
+		return getSize()==0;
+	}
+	public boolean isFull() {
+		return getSize()==5;
+	}
+	public static void main(String[] args) {
+
+
+	}
+
+}

Java_Programs_for_beginners/Queue/myDeque.java

@@ -0,0 +1,44 @@
+package Ds.Queue;
+
+public class myDeque<E> {
+	Node head , tail;
+	public void addHead(E data) {
+		Node <E> toAdd = new Node(data);
+		if(head==null) {
+			head = tail = toAdd;
+			return;
+		}
+		head.next = toAdd;
+		toAdd.previous = head;
+		toAdd= head;
+
+	}
+	public E removeLast() {
+		if(head==null) {
+			return null;
+		}
+		Node<E> toRemove = tail;
+		tail = tail.next;
+		tail.previous = null;
+
+		if(tail == null) {
+			head = null;
+		}
+		return toRemove.data;
+	}
+
+	public static class Node<E>{
+		E data;
+		Node next , previous;
+
+		public Node(E data) {
+			this.data = data;
+			this.next = this.previous = null;
+		}
+	}
+	public static void main(String[] args) {
+		// TODO Auto-generated method stub
+
+	}
+
+}

Java_Programs_for_beginners/Queue/priorityQueue.java

@@ -0,0 +1,50 @@
+package Ds.Queue;
+
+import java.util.*;
+
+public class priorityQueue {
+
+	public static void main(String[] args) {
+//		PriorityQueue <String> pq = new PriorityQueue();
+//		pq.add("orange");
+//		pq.add("apple");
+//		pq.add("hulalal");
+//		pq.add("hikli");
+//		pq.add("babul");
+//		
+//		System.out.println(pq);
+//		System.out.println(pq.remove());
+//		System.out.println(pq.remove());
+//		System.out.println(pq.remove());
+//		
+		Scanner sc = new Scanner(System.in);
+		int t = sc.nextInt();
+		while(t-- !=0) {
+			int n = sc.nextInt();
+			int k = sc.nextInt();
+			int a[] = new int [n];
+			for(int i = 0;i<n ; i++) {
+				a[i] = sc.nextInt();
+			}
+			PriorityQueue <Integer> pq = new PriorityQueue();
+			for(int i = 0;i<n ; i++) {
+				if(i<k) {
+					pq.add(a[i]);
+				}else {
+					if(pq.peek() < a[i]) {
+						pq.poll();
+						pq.add(a[i]);
+					}
+				}
+			}
+			ArrayList <Integer> ans = new ArrayList(pq);
+			Collections.sort(ans , Collections.reverseOrder());
+
+			for(int x: ans) {
+				System.out.print(x+" ");
+			}
+			System.out.println();
+		}
+	}
+
+}

Java_Programs_for_beginners/Queue/queue.java

@@ -0,0 +1,76 @@
+package Ds.Queue;
+
+import java.lang.reflect.Array;
+import java.util.ArrayList;
+
+public class queue {
+	private static final int n = 20;
+
+	  int [] arr;
+	  int front;
+	  int back;
+	  int size;
+
+	  public queue () {
+		arr = new int [n]; 
+		front = -1;
+		back = -1;
+	  }
+
+	  void push(int x) {
+		  if(back == n-1) {
+			  System.out.println("Queue overflow");
+			  return;
+		  }
+		  back++;
+		  arr[back]= x;
+		  size++;
+
+		  if(front == -1) {
+			  front++;
+		  }
+	  }
+	  void pop() {
+		  if(front == -1 || front> back) {
+			 System.out.println("No elements in queue");
+			  return;
+		  }
+		  size--;
+		  front++;
+
+	  }
+	  public void show() {
+			System.out.println("The number of elements are: ");
+			for(int i=0; i < size; i++) {
+				System.out.println(arr[front+ i]+ " ");
+			}
+		}
+	 int peek() {
+		  if(front == -1 || front> back) {
+				 System.out.println("No elements in queue");
+				  return -1;
+			  }
+		  return arr[front];
+	  }
+	 boolean empty() {
+		 if(front == -1 || front> back) {
+			  return true;
+		  }
+		 return false;
+	 }
+	 public static void main (String [] args) {
+			queue q = new queue();
+			q.push(1);
+			q.push(2);
+			q.push(3);
+			q.push(4);
+
+		   q.pop();
+			q.show();
+//			System.out.println(q.peek());
+//			q.pop();
+		}	
+
+
+
+}

Java_Programs_for_beginners/Queue/queueLL.java

@@ -0,0 +1,31 @@
+package Ds.Queue;
+
+import java.util.*;
+
+import Ds.LinkedList.MyLinkedList.Node;
+
+public class queueLL<E> {
+
+	private Node<E> head, rear;
+    public void enqueue(E e) {
+    	Node<E> toAdd = new Node(e);
+    	if(head==null) {
+    		head=rear= toAdd;
+    		return;
+    	}   	
+    	rear.next = toAdd;
+    	rear = rear.next;
+    }
+    public E dequeue(E e) {
+    	if(head==null) {
+    		return null;
+    	}
+    	Node<E> temp = head;
+    	 head= head.next;
+    	 if(head==null) {
+    		 rear = null;
+    	 }
+    	 return temp.data;
+
+    }
+}

Java_Programs_for_beginners/Queue/queueStack.java

@@ -0,0 +1,51 @@
+package Ds.Queue;
+
+import java.util.Stack;
+
+public class queueStack {
+
+//	public class que{
+	   Stack<Integer> s1 = new Stack();
+	   Stack<Integer> s2 = new Stack();
+
+	 public void push(int x) {
+		   s1.push(x);
+	   }
+	   public int pop() {
+		   if(s1.empty() && s2.empty()) {
+			   System.out.println("Queue is empty");
+			   return -1;
+		   }
+		   if(s2.empty()) {
+			   while(!s1.empty()) {
+				   s2.push(s1.peek());
+				   s1.pop();
+			   }
+		   }
+		   int top = s2.peek();
+		   s2.pop();
+		   return top;
+	   }
+	   boolean isEmpty() {
+		   if(s1.empty() && s2.empty()) {
+			   return true;
+		   }
+		   return false;
+	   }
+//	};
+	public static void main(String[] args) {
+		 queueStack q = new queueStack();
+//		que i = new que();
+		q.push(1);
+		q.push(2);
+		q.push(3);
+		q.push(4);
+
+		System.out.println(q.pop());
+		System.out.println(q.pop());	
+		System.out.println(q.pop());	
+		System.out.println(q.pop());
+
+		System.out.println(q.pop()); 
+	}
+}