Notes

#include <iostream>
#include <algorithm>
#include <iomanip>
#include <string.h>
using namespace std;

struct process {
int pid;
int arrival_time;
int burst_time;
int priority;
int start_time;
int completion_time;
int turnaround_time;
int waiting_time;
int response_time;
};

int main() {

int n;
struct process p[100];
float avg_turnaround_time;
float avg_waiting_time;
float avg_response_time;
float cpu_utilisation;
int total_turnaround_time = 0;
int total_waiting_time = 0;
int total_response_time = 0;
int total_idle_time = 0;
float throughput;
int burst_remaining[100];
int is_completed[100];
memset(is_completed,0,sizeof(is_completed));

cout << setprecision(2) << fixed;

cout<<"Enter the number of processes: ";
cin>>n;

for(int i = 0; i < n; i++) {
cout<<"Enter arrival time of process "<<i+1<<": ";
cin>>p[i].arrival_time;
cout<<"Enter burst time of process "<<i+1<<": ";
cin>>p[i].burst_time;
cout<<"Enter priority of the process "<<i+1<<": ";
cin>>p[i].priority;
p[i].pid = i+1;
burst_remaining[i] = p[i].burst_time;
cout<<endl;
}

int current_time = 0;
int completed = 0;
int prev = 0;

while(completed != n) {
int idx = -1;
int mx = -1;
for(int i = 0; i < n; i++) {
if(p[i].arrival_time <= current_time && is_completed[i] == 0) {
if(p[i].priority > mx) {
mx = p[i].priority;
idx = i;
}
if(p[i].priority == mx) {
if(p[i].arrival_time < p[idx].arrival_time) {
mx = p[i].priority;
idx = i;
}
}
}
}

if(idx != -1) {
if(burst_remaining[idx] == p[idx].burst_time) {
p[idx].start_time = current_time;
total_idle_time += p[idx].start_time - prev;
}
burst_remaining[idx] -= 1;
current_time++;
prev = current_time;

if(burst_remaining[idx] == 0) {
p[idx].completion_time = current_time;
p[idx].turnaround_time = p[idx].completion_time - p[idx].arrival_time;
p[idx].waiting_time = p[idx].turnaround_time - p[idx].burst_time;
p[idx].response_time = p[idx].start_time - p[idx].arrival_time;

total_turnaround_time += p[idx].turnaround_time;
total_waiting_time += p[idx].waiting_time;
total_response_time += p[idx].response_time;

is_completed[idx] = 1;
completed++;
}
}
else {
current_time++;
}
}

int min_arrival_time = 10000000;
int max_completion_time = -1;
for(int i = 0; i < n; i++) {
min_arrival_time = min(min_arrival_time,p[i].arrival_time);
max_completion_time = max(max_completion_time,p[i].completion_time);
}

avg_turnaround_time = (float) total_turnaround_time / n;
avg_waiting_time = (float) total_waiting_time / n;
avg_response_time = (float) total_response_time / n;
cpu_utilisation = ((max_completion_time - total_idle_time) / (float) max_completion_time )*100;
throughput = float(n) / (max_completion_time - min_arrival_time);

cout<<endl<<endl;

cout<<"#Pt"<<"ATt"<<"BTt"<<"PRIt"<<"STt"<<"CTt"<<"TATt"<<"WTt"<<"RTt"<<"n"<<endl;

for(int i = 0; i < n; i++) {
cout<<p[i].pid<<"t"<<p[i].arrival_time<<"t"<<p[i].burst_time<<"t"<<p[i].priority<<"t"<<p[i].start_time<<"t"<<p[i].completion_time<<"t"<<p[i].turnaround_time<<"t"<<p[i].waiting_time<<"t"<<p[i].response_time<<"t"<<"n"<<endl;
}
cout<<"Average Turnaround Time = "<<avg_turnaround_time<<endl;
cout<<"Average Waiting Time = "<<avg_waiting_time<<endl;
cout<<"Average Response Time = "<<avg_response_time<<endl;
cout<<"CPU Utilization = "<<cpu_utilisation<<"%"<<endl;
cout<<"Throughput = "<<throughput<<" process/unit time"<<endl;


}

/*

AT - Arrival Time of the process
BT - Burst time of the process
ST - Start time of the process
CT - Completion time of the process
TAT - Turnaround time of the process
WT - Waiting time of the process
RT - Response time of the process

Formulas used:

TAT = CT - AT
WT = TAT - BT
RT = ST - AT

*/

}