Queue done

Here are 10 Dart programs demonstrating the use of the Queue collection. A Queue is a collection designed for efficient insertion and removal of elements at both ends. It's part of the dart:collection library and is typically used in scenarios where you need FIFO (First In, First Out) operations, such as in queues for task scheduling or buffer handling.

To use a Queue, you need to import the dart:collection library.

import 'dart:collection';

void main() {

 Queue<String> tasks = Queue<String>();

 tasks.add('Task 1');

 tasks.add('Task 2');

 tasks.add('Task 3');

 print('Tasks: $tasks'); // Output: Tasks: {Task 1, Task 2, Task 3}

 String currentTask = tasks.removeFirst();

 print('Processing: $currentTask'); // Output: Processing: Task 1

 print('Remaining tasks: $tasks'); // Output: Remaining tasks: {Task 2, Task 3}

 print('First task: ${tasks.first}'); // Output: First task: Task 2

 print('Last task: ${tasks.last}'); // Output: Last task: Task 3

 tasks.addFirst('Urgent Task');

 print('Tasks after adding urgent task: $tasks'); // Output: Tasks after adding urgent task: {Urgent Task, Task 2, Task 3}

 tasks.removeLast();

 print('Tasks after removing last task: $tasks'); // Output: Tasks after removing last task: {Urgent Task, Task 2}

 print('Is queue empty? ${tasks.isEmpty}'); // Output: Is queue empty? false

 tasks.clear();

 print('Is queue empty after clearing? ${tasks.isEmpty}'); // Output: Is queue empty after clearing? true

}

1. Basic Queue Operations: Enqueue and Dequeue

import 'dart:collection';

void main() {

 Queue<String> queue = Queue();

 // Enqueue elements

 queue.add('Alice');

 queue.add('Bob');

 queue.add('Charlie');

 // Dequeue an element

 print("Dequeue: ${queue.removeFirst()}");

 // Remaining elements in the queue

 print("Queue after dequeue: $queue");

}

2. Adding Elements to Both Ends of a Queue

import 'dart:collection';

void main() {

 Queue<int> queue = Queue();

 // Enqueue elements

 queue.add(1);

 queue.add(2);

 queue.add(3);

 // Add an element to the front

 queue.addFirst(0);

 // Add an element to the end

 queue.addLast(4);

 print("Queue after adding elements: $queue");

}

3. Removing Elements from Both Ends of a Queue

import 'dart:collection';

void main() {

 Queue<int> queue = Queue.from([1, 2, 3, 4, 5]);

 // Remove the first element

 print("Removed from front: ${queue.removeFirst()}");

 // Remove the last element

 print("Removed from back: ${queue.removeLast()}");

 print("Queue after removals: $queue");

}

4. Iterating Over a Queue

import 'dart:collection';

void main() {

 Queue<String> queue = Queue.from(['Apple', 'Banana', 'Orange']);

 // Iterating through the queue

 for (var fruit in queue) {

   print(fruit);

 }

}

5. Peek the First and Last Element of a Queue

import 'dart:collection';

void main() {

 Queue<int> queue = Queue.from([10, 20, 30, 40, 50]);

 // Peek the first element without removing it

 print("First element: ${queue.first}");

 // Peek the last element without removing it

 print("Last element: ${queue.last}");

}

6. Check if Queue is Empty or Not

import 'dart:collection';

void main() {

 Queue<String> queue = Queue.from(['John', 'Paul', 'George']);

 if (queue.isEmpty) {

   print("The queue is empty.");

 } else {

   print("The queue has ${queue.length} elements.");

 }

 // Remove all elements to make it empty

 queue.clear();

 if (queue.isEmpty) {

   print("The queue is now empty.");

 }

}

7. Using addAll() to Add Multiple Elements

import 'dart:collection';

void main() {

 Queue<String> queue = Queue();

 // Add multiple elements at once

 queue.addAll(['Alice', 'Bob', 'Charlie']);

 print("Queue after addAll: $queue");

}

8. Reversing a Queue

import 'dart:collection';

void main() {

 Queue<int> queue = Queue.from([1, 2, 3, 4, 5]);

 // Reverse the queue

 var reversedQueue = Queue<int>.from(queue.reversed);

 print("Reversed Queue: $reversedQueue");

}

9. Using Queue for Task Scheduling (FIFO)

import 'dart:collection';

void main() {

 Queue<String> taskQueue = Queue();

 // Add tasks to the queue

 taskQueue.add('Task 1');

 taskQueue.add('Task 2');

 taskQueue.add('Task 3');

 // Process tasks in FIFO order

 while (taskQueue.isNotEmpty) {

   String task = taskQueue.removeFirst();

   print("Processing: $task");

 }

}

10. Check the Length of a Queue

import 'dart:collection';

void main() {

 Queue<int> queue = Queue.from([10, 20, 30]);

 // Print the length of the queue

 print("Length of the queue: ${queue.length}");

 // Add more elements

 queue.add(40);

 queue.add(50);

 // Print the updated length

 print("Updated length of the queue: ${queue.length}");

}

Explanation of Key Operations:

1. add(): Adds an element to the end of the queue.

2. addFirst(): Adds an element to the front of the queue.

3. addLast(): Adds an element to the back of the queue.

4. removeFirst(): Removes and returns the first element from the queue.

5. removeLast(): Removes and returns the last element from the queue.

6. first and last: Allows peeking at the first and last elements without removing them.

7. clear(): Removes all elements from the queue.

8. isEmpty: Checks whether the queue is empty.

9. length: Returns the number of elements in the queue.

10. addAll(): Adds multiple elements to the queue in one operation.

These programs highlight the powerful features of the Queue class in Dart. It's ideal for scenarios where you need a collection that supports efficient first-in, first-out (FIFO) behavior, like task processing or managing buffers.