We can add items to the tail of our queue, but we remove them from the head using a method known as dequeue(), which is another way to say “remove from a queue”. Like enqueue(), we care about the size of the queue — but in the other direction, so that we prevent queue “underflow”. After all, you don’t want to remove something that isn’t there!
As with peek(), our dequeue() method should return the value of the head. Unlike, peek(), dequeue() will also remove the current head and replace it with the following node.
For dequeue, there are three scenarios that we will take into account:
- The queue is empty, so we cannot remove or return any nodes lest we run into queue “underflow”
- The queue has one node, so when we remove it, the queue will be empty and we need to reset the queue’s
headandtailtoNone - The queue has more than one node, and we just remove the
headnode and reset theheadto the following node
Instructions
Inside the Queue class you built, define a method dequeue().
- Add an
ifclause to check if the queue is not empty - If so, set a new variable
item_to_removeto the currenthead - Inside your
ifstatement, print: “Removing “ +str(item_to_remove.get_value())+ “ from the queue!”
Inside the if statement, below your print statement, check if the size is 1.
- If so, give the queue’s
headandtaila value ofNone - Otherwise, set the queue’s
headequal to the following node usingNode‘s handy dandyget_next_node()method
Outside of the inner if/else clause
- reduce the queue’s
sizeby 1 - use
Node‘sget_value()method to return the value ofitem_to_remove
After the outermost if statement, create an else statement. Within it, print “This queue is totally empty!”