A priority queue is a queue in which each element has a priority. For example, when passengers are waiting in a queue to board a flight, families with young children and business class passengers usually take priority and board first; then, the economy class passengers board. Let's look at another example. Suppose that three people are waiting in a queue to be attended to at a service counter, and an old man steps in at the end of the queue. Considering his age, the people in the queue might give him a higher priority and allow him to go first. Through these two examples, we can see that the elements in a priority queue have priorities, and they are processed in order of those priorities.
Just like in queuing, ...
