Discrete Event Simulation

/*
 * Usage : './a.out 10'
 * where 10 is the number of customers
 */
#include<iostream>
#include<stdlib.h>
#define FOR(n) for(int i=0;i<(n);i++)
#define TAB "\t"
using namespace std;
int main(int argc, char *argv[]) {
  struct event {
    int id;
    float arrival_time, service_time, start_time, dept_time, server_idle_time, time_in_queue, total_time;
  } e[100];
  int n=atoi(argv[1]);
  //Get inputs
  cout<<"Input method : arrival_time<TAB>service_time"<<endl;
  cout<<"Arrival\tService"<<endl;
  cout<<"Time\tTime"<<endl;;
  FOR(n){
    e[i].id = i+1;
    cin>>e[i].arrival_time>>e[i].service_time;
  }
  //Populate
  FOR(n){
    if(0==i || e[i-1].dept_time < e[i].arrival_time)
      e[i].start_time = e[i].arrival_time;
    else
      e[i].start_time = e[i-1].dept_time;
    e[i].dept_time = e[i].start_time + e[i].service_time;
    e[i].time_in_queue = e[i].start_time - e[i].arrival_time;
    e[i].total_time = e[i].dept_time - e[i].arrival_time;
    e[i].server_idle_time = e[i].arrival_time - (0==i ? 0 : e[i-1].dept_time);
    e[i].server_idle_time = e[i].server_idle_time > 0 ? e[i].server_idle_time : 0;
  }
  //Output
  cout<<"Cust\tArrival\tStart\tDept\tServer\tTime in\tTotal"<<endl;
  cout<<"ID\tTime\tService\tTime\tIdle\tQueue\tTime"<<endl;
  FOR(n){
    cout<<e[i].id<<TAB<<e[i].arrival_time<<TAB<<e[i].start_time<<TAB<<e[i].dept_time<<TAB<<e[i].server_idle_time<<TAB<<e[i].time_in_queue<<TAB<<e[i].total_time<<endl;
  }

  return 0;
}