RoundRobinScheduling.cpp

//Round Robin Scheduling.
/*Round robin is designed specifically for time sharing systems. 
It is similar to first come first serve scheduling algorithm but the preemption is the added
functionality to switch between the processes.
A small unit of time also known as time slice or quantum is set/defined.
CPU makes sure, time slices ( any natural number ) are assigned  to each process in equal portions
and in circular order , dealing with all process without any priority.
The RR Scheduling Algorithm is Starvation Free, i.e no process is left waiting for its turn to be executed by the CPU .*/

#include<bits/stdc++.h>
//macro defination for "for loop"
#define f(i,n) for(int i=0;i<n;i++)
using namespace std;
int main()
{
	cout<<"Enter Number of Processes : ";
	int p;
	cin>>p;
	//vector declaration with initial values 0 of size p
	vector<int> processes(p,0);
	vector<int> wt(p,0); //vector to store waiting time
	vector<int> tat(p,0); //vector to store turn around time
	f(i,p)processes[i]=i+1;
	vector<int> burst(p); //vector to store burst time
	f(i,p) cin>>burst[i];
	//take the time quantum input
	cout<<"Enter Time Quantum : ";
	int tq;
	cin>>tq;
	vector<int> rbt(p); //vector to store remaining burst time
	f(i,p) rbt[i] = burst[i];
	int t=0; //time variable initialized to zero
	while (1)
    {
        bool flg = true;// flag variable used later to break form while loop
        f(i,p)
        {
            if (rbt[i] > 0) //If there is some burst time remaining for the process we need to further consider it.
            {
                flg = false;
                if (rbt[i] > tq)
                {
                    t += tq;
                    rbt[i] -= tq; // Remaining burst time = Remaining burst time - Time quantum for which it ran 
                }
                else
                {
                    t = t + rbt[i];
                    wt[i] = t - burst[i]; //Waiting time calculation
                    rbt[i] = 0;
                }
            }
        }
        if (flg == true)
          break;
    }
    int total_wt=0, total_tat=0;
    f(i,p) tat[i]=burst[i]+wt[i]; // turn around time calculation
    f(i,p){
    	total_wt = total_wt+wt[i];
    	total_tat = total_tat+tat[i];
	}
	cout<<endl;
	cout<<"Burst Time	Wating Time		Turn Around Time"<<endl;
	f(i,p)cout<<burst[i]<<"				"<<wt[i]<<"				"<<tat[i]<<endl;
	cout<<"Average Waiting Time : "<<total_wt/p<<endl;
	cout<<"Average Turn Around Time : "<<((float)total_tat/(float)p);
}