roundrobin.cpp

#include <iostream>
using namespace std;

void findWaitingTime(int processes[], int n,
    int bt[], int wt[], int quantum)
{

    int rem_bt[n];
    for (int i = 0; i < n; i++)
        rem_bt[i] = bt[i];

    int t = 0; 
    while (1)
    {
        bool done = true;

        for (int i = 0; i < n; i++)
        {
            if (rem_bt[i] > 0)
            {
                done = false; 
                if (rem_bt[i] > quantum)
                {
                    t += quantum;
                    rem_bt[i] -= quantum;
                }

                else
                {
                    t = t + rem_bt[i];
                    wt[i] = t - bt[i];
                    rem_bt[i] = 0;
                }
            }
        }

        if (done == true)
            break;
    }
}

void findTurnAroundTime(int processes[], int n,
                        int bt[], int wt[], int tat[])
{
    for (int i = 0; i < n; i++)
        tat[i] = bt[i] + wt[i];
}

void findavgTime(int processes[], int n, int bt[], int quantum)
{
    int wt[n], tat[n], total_wt = 0, total_tat = 0;
    findWaitingTime(processes, n, bt, wt, quantum);
    findTurnAroundTime(processes, n, bt, wt, tat);

    cout << "PN\t "
         << " \tBT "
         << " WT "
         << " \tTAT\n";

    for (int i = 0; i < n; i++)
    {
        total_wt = total_wt + wt[i];
        total_tat = total_tat + tat[i];
        cout << " " << i + 1 << "\t\t" << bt[i] << "\t "
             << wt[i] << "\t\t " << tat[i] << endl;
    }

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

int main()
{
    int processes[] = {1, 2, 3,4,5};
    int n = sizeof processes / sizeof processes[0];
    int burst_time[] = {4,1,5,2,3};
    int quantum = 3;
    findavgTime(processes, n, burst_time, quantum);
    return 0;
}