ReadyQueue: Ready queue is a queue of PCBs that are in the READY state, which are to be scheduled to run on the CPU. It is a priority queue such that the process $($PCB$)$ with the highest priority can be selected next. It should support at least the following member functions:

addPCB: add a PCB into the ready

removePCB: remove and return the PCB with the highest priority from the queue

size: return the number of elements in the queue

displayAll: Display the IDs and priorities of processes in the queue.