How do priority queues operate differently from standard queues?

Priority queues operate differently from standard queues by assigning a priority to each element and serving them based on this priority.

In a standard queue, elements are added at the end and removed from the front, following the First-In-First-Out (FIFO) principle. This means that the element that has been in the queue the longest is the first one to be removed. However, a priority queue does not strictly follow this principle. Instead, it assigns a priority to each element upon entry. When an element is to be removed, the element with the highest priority is removed first. If two elements have the same priority, then they are served based on their order in the queue, similar to a standard queue.

The priority of an element in a priority queue can be determined by various factors depending on the specific application. For example, in a hospital emergency room, patients with more severe conditions would be assigned a higher priority than those with less severe conditions. In a computer system, processes that require immediate attention could be assigned a higher priority.

The implementation of a priority queue can be done using different data structures such as arrays, linked lists, or heaps. The choice of data structure can affect the efficiency of operations such as insertion, deletion, and search. For example, a binary heap can perform insert and delete operations in logarithmic time, making it an efficient choice for implementing a priority queue.

In summary, the main difference between a priority queue and a standard queue lies in how elements are served. While a standard queue follows the FIFO principle, a priority queue serves elements based on their priority. This makes priority queues a useful tool in scenarios where some elements need to be served before others, regardless of their order of arrival.