This program simulates a simple CPU scheduling algorithm that executes a set of processes with different arrival times, CPU burst times, and priorities. It sorts the processes by their arrival time and priority using a merge sort algorithm and simulates their execution in a loop. The program selects the process with the highest priority at each iteration, updates its remaining time, and adds it to the PCB array. After all processes have been executed, the program calculates performance metrics and writes them to a file. The important concepts used are the CPU scheduling algorithm, the PCB array, and the merge sort algorithm.