Compare and contrast the Round Robin $($RR$)$ scheduling algorithm with the Shortest Job Next $($SJN$)$ scheduling algorithm. Discuss their advantages, disadvantages, and scenarios where each algorithm might be preferred.

Consider the following set of processes, with the length of the CPU burst given in milliseconds and their priorities:

$\backslash$table$[[$Process$,$Burst Time,Priority$],[$P$1,5,4],[$P$2,3,1],[$P$3,1,2],[$P$4,7,2],[$P$5,4,3]]$

The processes are assumed to have arrived in the order P$1,$ P$2,$ P$3,$ P$4,$ P$5,$ all at time $0.$ Using the Priority Scheduling algorithm, calculate the average waiting time for these processes.