Program for Priority Scheduling | Set 1

// C++ program for implementation of FCFS

// 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

};

// Function to sort the Process acc. to priority

bool comparison(Process a, Process b)

{

    return (a.priority > b.priority);

}

// Function to find the waiting time for all

// processes

void findWaitingTime(Process proc[], int n,

                     int wt[])

{

    // waiting time for first process is 0

    wt[0] = 0;

    // calculating waiting time

    for (int  i = 1; i < n ; i++ )

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

}

// Function to calculate turn around time

void findTurnAroundTime( Process proc[], int n,

                         int wt[], int tat[])

{

    // calculating turnaround time by adding

    // bt[i] + wt[i]

    for (int  i = 0; i < n ; i++)

        tat[i] = proc[i].bt + wt[i];

}

//Function to calculate average time

void findavgTime(Process proc[], int n)

{

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

    //Function to find waiting time of all processes

    findWaitingTime(proc, n, wt);

    //Function to find turn around time for all processes

    findTurnAroundTime(proc, n, wt, tat);

    //Display processes along with all details

    cout << "\nProcesses  "<< " Burst time  "

         << " Waiting time  " << " Turn around time\n";

    // Calculate total waiting time and total turn

    // around time

    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 processes by priority

    sort(proc, proc + n, comparison);

    cout<< "Order in which processes gets executed \n";

    for (int  i = 0 ; i <  n; i++)

        cout << proc[i].pid <<" " ;

    findavgTime(proc, n);

}

// Driver code

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;

}