4. Priority cpu scheduling

#include <bits/stdc++.h>

using namespace std;

struct Process {

int pid; // Process ID

int bt; // CPU Burst time required

int priority; // Priority of this process

};

bool comparison(Process a, Process b)

{

return (a.priority > b.priority);

}

void findWaitingTime(Process proc[], int n, int wt[])

{

wt[0] = 0;

for (int i = 1; i < n; i++)

wt[i] = proc[i - 1].bt + wt[i - 1];

}

void findTurnAroundTime(Process proc[], int n, int wt[], int tat[])

{

for (int i = 0; i < n; i++)

tat[i] = proc[i].bt + wt[i];

}

void findavgTime(Process proc[], int n)

{

int wt[n], tat[n], total_wt = 0, total_tat = 0;

findWaitingTime(proc, n, wt);

findTurnAroundTime(proc, n, wt, tat);

cout << "\nProcesses " << " Burst time " << " Waiting time " << " Turn around time\n";

for (int i = 0; i < n; i++) {

total_wt = total_wt + wt[i];

total_tat = total_tat + tat[i];

cout << " " << proc[i].pid << "\t\t" << proc[i].bt << "\t " << wt[i] << "\t\t " << tat[i] << endl;

}

cout << "\nAverage waiting time = " << (float)total_wt / (float)n;

cout << "\nAverage turn around time = " << (float)total_tat / (float)n;

}

void priorityScheduling(Process proc[], int n)

{

sort(proc, proc + n, comparison);

cout << "Order in which processes get executed:\n";

for (int i = 0; i < n; i++)

cout << proc[i].pid << " ";

findavgTime(proc, n);

}

int main()

{

Process proc[] = { { 1, 10, 2 }, { 2, 5, 0 }, { 3, 8, 1 } };

int n = sizeof proc / sizeof proc[0];

priorityScheduling(proc, n);

return 0;

}

output :-