CC-12 : Remove element from Queue and preserve order of rest of elements of Queue.

Description:

Given a Queue, remove requested element from it and preserve order of rest of elements of the Queue.

Test cases and expected outputs:

Input Parameters	Expected outputs
Queue< Integer > queue=new LinkedList< Integer >(); System.out.println("Add to Queue:"); queue.add(9); queue.add(14); queue.add(17); queue.add(34); queue.add(21); queue.add(28); queue.add(21); printQueue(queue); QueueRemoveElement queueRemoveElement =new QueueRemoveElement(); System.out.println("Remove: 17"); queueRemoveElement. queueRemoveElement(queue,17); printQueue(queue); System.out.println("Remove: 21"); queueRemoveElement. queueRemoveElement(queue,21);	Add to Queue: Queue nodes: 9 <- 14 <- 17 <- 34 <- 21 <- 28 <- 21 <- Remove: 17 Queue nodes: 9 <- 14 <- 34 <- 21 <- 28 <- 21 <- Remove: 21 Queue nodes: 9 <- 14 <- 34 <- 28 <-

Input Parameters

Expected outputs

Queue< Integer > queue=new LinkedList< Integer >();
System.out.println("Add to Queue:");
queue.add(9);
queue.add(14);
queue.add(17);
queue.add(34);
queue.add(21);
queue.add(28);
queue.add(21);
printQueue(queue);
QueueRemoveElement queueRemoveElement =new QueueRemoveElement();
System.out.println("Remove: 17");
queueRemoveElement. queueRemoveElement(queue,17);
printQueue(queue);
System.out.println("Remove: 21");
queueRemoveElement. queueRemoveElement(queue,21);

Add to Queue:
Queue nodes: 9 <- 14 <- 17 <- 34 <- 21 <- 28 <- 21 <-
Remove: 17
Queue nodes: 9 <- 14 <- 34 <- 21 <- 28 <- 21 <-
Remove: 21
Queue nodes: 9 <- 14 <- 34 <- 28 <-

Pseudocode:

Using a for loop iterate through all elements of input Queue:

If current nodes data == element to be removed, then remove it from the Queue.

If current nodes data != element to be removed, then remove it from the start of Queue and add it to end of Queue.

Code:

public Queue< Integer > queueRemoveElement(Queue< Integer > queue, int toRemove) {
	int curr=0; int qSize=queue.size();
	for (int idx=0;idx < qSize ; idx++) {
		curr=queue.remove();
		if (curr != toRemove) {
			queue.add(curr);
		}
	}
	return queue;
}

Click here to download and run code and test cases !

Below fully running code can be copied and run on Eclipse or other Java IDEs. Refer the classname in code below. If the class name below is "A", save the code below to a file named A.java before running it. Be sure to try your own test cases to enhance your understanding ! You can also tweak the code to optimize or add enhancements and custom features.

import java.util.Queue;
import java.util.Iterator;
import java.util.LinkedList;


public class QueueRemoveElement {
	
public Queue<Integer> queueRemoveElement(Queue<Integer> queue, int toRemove) {
	int curr=0; int qSize=queue.size();
	for (int idx=0;idx < qSize ; idx++) {
		curr=queue.remove();
		if (curr != toRemove) {
			queue.add(curr);
		}
	}
	return queue;
}

public static void printQueue(Queue<Integer> queue) throws Exception   {
    if (queue.size() == 0) { System.out.println("Queue empty"); return; }
    System.out.println();
	System.out.println("*********************************************************************");
	System.out.print("Queue nodes: ");
	Iterator itr=queue.iterator();
	while (itr.hasNext())  {
	    System.out.print(itr.next());
	    System.out.print(" <- ");
	} 
	System.out.println();
	System.out.println("*********************************************************************");
	System.out.println();
	Thread.sleep(2000);
	return;
}
  	
public static void main(String[] args) {
	try {
	Queue<Integer> queue=new LinkedList<Integer>();
	System.out.println("Add to Queue:");
	queue.add(9);
	queue.add(14);
	queue.add(17);
	queue.add(34);
	queue.add(21);
	queue.add(28);
	queue.add(21);
	printQueue(queue);
	
	QueueRemoveElement queueRemoveElement=new QueueRemoveElement();
	System.out.println("Remove: 17");
	queue=queueRemoveElement.queueRemoveElement(queue,17);
	printQueue(queue);
	System.out.println("Remove: 21");
	queue=queueRemoveElement.queueRemoveElement(queue,21);
	printQueue(queue);

	}catch (Exception exception) {
	System.out.print("Exception: "+ exception);
	}
		
	}
	
}