teller.cpp

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#include <queue>
#include <iostream>
#include <vector>
 
#include <teller.h>
 
//  A very unsatisfactory, but very portable implementation
//  of a linear congruential pseudorandom number generator.
//  (Apologies to D. Lehmer, D. Knuth, R. Sedgewick, et al.)
static unsigned long int lcg_seed = 0;
inline int lcg_rand (int n)
{
    lcg_seed = ((lcg_seed * 11321) + 1) % 32575;
    return (int) (((double) lcg_seed / 32575.0) * n);
}
 
int main ()
{
    const int numberOfTellers = 5;
    const int numberOfMinutes = 60;
    double totalWait          = 0;
    int numberOfCustomers     = 0;
 
    std::vector<Teller> teller (numberOfTellers);
    std::queue<Customer> line;
 
    for (int t = 0; t < numberOfMinutes; t++) {
        if (lcg_rand (10) < 9)
            line.push (Customer (t));
        
        for (int i = 0; i < numberOfTellers; i++) {
            if (teller[i].isFree () && !line.empty ()) {
                Customer& frontCustomer = line.front ();
                numberOfCustomers++;
                totalWait += t - frontCustomer.arrivalTime;
                teller[i].addCustomer (frontCustomer);
                line.pop ();
            }
        }
    }
 
    std::cout << "average wait: "
              << (totalWait / numberOfCustomers) << std::endl;
 
    return 0;
}