#include <stdio.h>
#include <iostream>

using namespace std;

struct process
{
    int pid;          // Process ID
    int burst_time;   // CPU Burst Time
    int working_time; // Time this process executed, if  working_time==burst_time, process is complete
    int t_round;      // turn around time, time needed for the process to complete
    int arrivalTime;  // time for a process to arrive to queue, which is zero in this case
    int remainTime;   // time remaining for a process to complete execution
};

main()
{
    int numProcesses;
    cout << "Enter the number of processes: ";
    cin >> numProcesses;
    struct process pr[numProcesses];

    int i, totalExecutionTime = 0, timeQuantum, flag = 0, n;
    float totalWaitingTime = 0;

    for (i = 0; i < numProcesses; i++)
    {
        cout << "\nEnter PID for process " << i + 1 << " (ms): ";
        cin >> pr[i].pid;

        cout << "\nEnter Burst Time for process " << i + 1 << " (ms): ";
        cin >> pr[i].burst_time;
    }

    // arrival time is zero
    for (int i = 0; i < numProcesses; i++)
    {
        pr[i].arrivalTime = 0;
    }

    printf("\nEnter Time Quantum: ");
    scanf("%d", &timeQuantum);

    printf("\n");
    for (i = 0; numProcesses != 0;)
    {
        /**
         * this below condition check the remain time for any process is less than or equal with the time quantum
         * or not and also check the remain time is greater than 0 or not. if both condition are true that means
         * the process can execute fully at one time.
         */
        if (pr[i].remainTime <= timeQuantum && pr[i].remainTime > 0)
        {
            totalExecutionTime += pr[i].remainTime;
            pr[i].remainTime = 0;
            flag = 1;
        }

        else if (pr[i].remainTime > 0)
        {
            pr[i].remainTime -= timeQuantum;
            totalExecutionTime += timeQuantum;
        }

        if (flag == 1 && pr[i].remainTime == 0)
        {
            printf("P[%d] | waiting Time : %d\n", i + 1, totalExecutionTime - pr[i].burst_time);
            totalWaitingTime += totalExecutionTime - pr[i].burst_time;
            flag = 0;
            numProcesses--;
        }

        if (i == n - 1)
            i = 0;
        else if (pr[i + 1].arrivalTime <= totalExecutionTime)
        {
            i++;
        }
        else
            i = 0;
    }

    totalWaitingTime = (float)totalWaitingTime / n;
    printf("\nThe Average Waiting Time : %.2f \n", totalWaitingTime);
}