Deque is short for “double ended queue”. With an ordinary queue, you add things to one end and take them from the other. With a double ended queue, you can add things to either end, and take them from either end. That makes it a bit more versatile; for example, you could use it as … Read more
This looks like a good candidate for the TAILQ_* ? “man queue” will give more details – there are simple lists, tail queues and circular queues there. Those are the macros that you’d need to bolt on your own structures, not classes of course. The code for your scenario will look something like this (I … Read more
Java queues don’t have enqueue and dequeue methods, these operations are done using the following methods: Enqueuing: add(e): throws exception if it fails to insert the object offer(e): returns false if it fails to insert the object Dequeuing: remove(): throws exception if the queue is empty poll(): returns null if the queue is empty Take … Read more
The Queue module implements multi-producer, multi-consumer queues. It is especially useful in threaded programming when information must be exchanged safely between multiple threads. As you can see, the Queue module was created specifically for use with threads, providing only FIFO, LIFO and priority queues, none of which provide this functionality. However by examining the source … Read more
A Queue is an interface, which means you cannot construct a Queue directly. The best option is to construct off a class that already implements the Queue interface, like one of the following: AbstractQueue, ArrayBlockingQueue, ArrayDeque, ConcurrentLinkedQueue, DelayQueue, LinkedBlockingQueue, LinkedList, PriorityBlockingQueue, PriorityQueue, or SynchronousQueue. An alternative is to write your own class which implements the necessary Queue interface. It is not needed except in those rare cases where you wish to … Read more
This is my main method for a stacks/queues assignment. I keep getting an error with my queue, but not my Stack. The stack class seems to be working just fine. I’m completely stuck. It says “cannot instantiate type Queue”. Any help would be most appreciated!
As Uri Goren astutely noted above, the Python stdlib already implemented an efficient queue on your fortunate behalf: collections.deque. What Not to Do Avoid reinventing the wheel by hand-rolling your own: Linked list implementation. While doing so reduces the worst-case time complexity of your dequeue() and enqueue() methods to O(1), the collections.deque type already does so. It’s also thread-safe and presumably more space and time … Read more
Yeah. Queue LinkedList being the most trivial concrete implementation.
You do This imports all the classes from the queue module already. Change that line to CAREFUL: “Wildcard imports (from import *) should be avoided, as they make it unclear which names are present in the namespace, confusing both readers and many automated tools”. (Python PEP-8) As an alternative, one could use: