SystemsProgrammingAndOperatingSystem/Codes/Group B/Assignment - 5/SJF (Preemptive).cpp

#include<iostream>
#include<limits.h> // for INT_MAX
using namespace std;

struct sjf{
    int burst, arrival, id, completion, waiting, turnaround, response;
    bool active;
};

sjf meh[30];

class lesgo{
public:
    int n;

    void sjfIn(){
        cout<<"\nEnter number of processes: ";
        cin>>n;
        for(int i = 1; i <= n; i++){
            cout<<"\nEnter arrival time of P"<<i<<": ";
            cin>>meh[i].arrival;
            cout<<"\nEnter burst time of P"<<i<<": ";
            cin>>meh[i].burst;
            meh[i].id = i;
            meh[i].active = false;
        }
        cout<<"\n  | Arrival | Burst\n";
        for(int j = 1; j <= n; j++) {
            cout<<"P"<<j<<"| "<<meh[j].arrival<<"       | "<<meh[j].burst<<"\n";
        }
    }

    void sjfProcess(){
        int k = 0;
        int completed = 0;
        cout<<"\nSequence of processes is: ";
        while(completed < n){
            int burst1 = INT_MAX; // Initialize to the maximum possible value
            int iddd = -1;
            for(int i = 1; i <= n; i++){
                if(meh[i].arrival <= k && meh[i].burst > 0){
                    if(meh[i].burst < burst1){
                        burst1 = meh[i].burst;
                        iddd = i;
                    }
                }
            }
            if(iddd != -1){
                // Mark the process as active
                if(!meh[iddd].active) {
                    meh[iddd].response = k - meh[iddd].arrival;
                    meh[iddd].active = true;
                }
                
                cout<<"P"<<iddd<<" ";
                meh[iddd].burst--;
                k++;
                if(meh[iddd].burst == 0){
                    meh[iddd].completion = k;
                    meh[iddd].turnaround = meh[iddd].completion - meh[iddd].arrival;
                    meh[iddd].waiting = meh[iddd].turnaround - (meh[iddd].response + 1); // +1 for the final unit burst time
                    completed++;
                }
            } else{
                k++;
            }
        }
    }

    void displayMetrics(){
        double totalWaiting = 0, totalTurnaround = 0, totalCompletion = 0;

        cout<<"\n\n  | Completion time | Waiting time | Turnaround time | Response time\n";
        for(int j = 1; j <= n; j++) {
            totalWaiting += meh[j].waiting;
            totalTurnaround += meh[j].turnaround;
            totalCompletion += meh[j].completion;
            cout<<"P"<<j<<"| "<<meh[j].completion
                <<"             | "<<meh[j].waiting
                <<"             | "<<meh[j].turnaround
                <<"             | "<<meh[j].response<<"\n";
        }

        cout<<"\nAverage completion time: "<<totalCompletion/n;
        cout<<"\nAverage waiting time: "<<totalWaiting/n;
        cout<<"\nAverage turnaround time: "<<totalTurnaround/n;
    }
};

int main(){
    lesgo obj;
    obj.sjfIn();
    obj.sjfProcess();
    obj.displayMetrics();
    return 0;
}