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#include <iostream>
#include <cstdlib>
#include <queue>
#include <fstream>
#include <ctime>
using namespace std;
// Input parameters
#define SIMULATION_TIME 0
#define ARRIVAL_RATE 1
#define MIN_SERVICE_TIME 2
#define MAX_SERVICE_TIME 3
#define MAX_LINE_SIZE 4
#define ANGRY_THRESHOLD 5
#define PARAMS_MAX 6
#define FILENAME "sim.txt"
// Or like this:
// const int SIMULATION_TIME = 0;
// Or make 6 variables:
// double SIMULATION_TIME = 0;
// Counters -- indexes into variable 'counters' below
#define CUSTOMERS_SERVICED 0
#define CUSTOMERS_LEAVING 1
#define AVERAGE_WAIT 2
#define AVERAGE_LINE 3
#define ANGRY_CUSTOMERS 4
#define COUNTERS_MAX 5
// Holds the current simulation parameters
double parameters[PARAMS_MAX];
double counters[COUNTERS_MAX];
// This is an example debug macro you can use to print
// things each time through the loop
#define DEBUGGING_ENABLED 1
#ifdef DEBUGGING_ENABLED
#define DEBUG(x) do { \
cerr << __FILE__ << ": " << __LINE__ << ": " << x << endl; \
} while (0)
#else
#define DEBUG(x)
#endif // DEBUGGING_ENABLED
// Return the service interval, between 'min'
// and 'max'.
int randomInt(int min, int max)
{
return (rand() % (max - min) + min);
}
// Returns TRUE if a customer arrived during this minute
bool randomChance(double prob)
{
double rv = rand() / (double(RAND_MAX) + 1);
return (rv < prob);
}
// Read the next simulation from the file. Return
// TRUE if one could be read, FALSE otherwise (eof).
bool readNextSim(fstream &f, double parameters[])
{
for (int i = 0; i < PARAMS_MAX; i++)
{
string tmp;
getline(f, tmp);
if (f.eof())
return false;
// Read in the next parameter
parameters[i] = atof(tmp.c_str());
}
for (int i = 0; i < 5; i++)
cout <<"Simulation Results #" << i + 1 << endl;
cout << "---------------------" << endl;
cout << "\t Overall simulation time: " << "\t" << parameters[SIMULATION_TIME] << endl;
cout << "\t Arrival rate: " << "\t\t\t" << parameters[ARRIVAL_RATE] << endl;
cout << "\t Minimum service time: " << "\t\t" << parameters[MIN_SERVICE_TIME] << endl;
cout << "\t Maximum service time: " << "\t\t" << parameters[MAX_SERVICE_TIME] << endl;
cout << "\t Maximum line size: " << "\t\t" << parameters[MAX_LINE_SIZE] << endl;
cout << "\t Angry threshold: " << "\t\t" << parameters[ANGRY_THRESHOLD] << endl;
return true;
}
int main()
{
fstream f(FILENAME);
// Seed the random number generator here
srand(time(0));
if (!f.good())
{
cout << "Invalid file." << endl;
return -1;
}
while (readNextSim(f, parameters))
{
// Run the next simulation
queue<int> line;
for (int i = 0; i < COUNTERS_MAX; i++)
counters[i] = 0;
// or:
// memset(counters, 0, COUNTERS_MAX * sizeof(double));
//int customersLeavingLineFull = 0;
int simTime = 0;
int currentCustomer = -1;
// Each time through this loop represents 1 minute passing.
// There needs to be code to handle everything that can happen
// in 1 minute:
// - Customer arriving (yes/no?)
// - Is the current customer finished
// - Possibly process the next person in line
// - Calculate simulation statistics along the way
while (simTime++ < parameters[SIMULATION_TIME])
{
// One iteration of the loop represents one
// minute of simulation time.
// Check to see if a customer arrived
// (if so, process, also see if the line is full)
bool arrived = randomChance(parameters[ARRIVAL_RATE]);
if (arrived)
{
// A customer arrived in this minute
if (currentCustomer == -1)
{
// No customer is currently at the cashier
int serviceTime = randomInt(parameters[MIN_SERVICE_TIME],
parameters[MAX_SERVICE_TIME]);
currentCustomer = simTime + serviceTime;
}
else
{
if (line.size() == parameters[MAX_LINE_SIZE])
{
// Count this customer as leaving because the line is too
// full
counters[CUSTOMERS_LEAVING]++;
}
else
{
line.push(simTime);
}
}
}
counters[AVERAGE_LINE] += line.size();
// Check to see if the current customer is done
// at the cashier. Also check if there is no customer
// at the cashier (in which the next customer goes to the
// cashier).
if (simTime == currentCustomer)
{
if (!line.empty())
{
int nextCustomerTimestamp = line.front();
int waitingTime = simTime - nextCustomerTimestamp;
// We need to include this in the average waiting times
if (waitingTime >= parameters[ANGRY_THRESHOLD])
counters[ANGRY_CUSTOMERS]++;
counters[AVERAGE_WAIT] += waitingTime;
// Set currentCustomer to the time when that customer
// will be done. Need to call randomInt().
int serviceTime = randomInt(parameters[MIN_SERVICE_TIME],
parameters[MAX_SERVICE_TIME]);
// This will give us a timestamp of when the current customer will
// be done.
currentCustomer = simTime + serviceTime;
line.pop();
counters[CUSTOMERS_SERVICED]++;
}
else
{
// The line is empty
counters[CUSTOMERS_SERVICED]++;
currentCustomer = -1;
}
}
}
// Print a summary of the simulation:
// counters
counters[AVERAGE_WAIT] /= counters[CUSTOMERS_SERVICED];
counters[AVERAGE_LINE] /= parameters[SIMULATION_TIME];
cout << endl;
cout << "\t Customers serviced: " << "\t\t" << counters[CUSTOMERS_SERVICED] << endl;
cout << "\t Customers leaving: " << "\t\t" << counters[CUSTOMERS_LEAVING] << endl;
cout << "\t Average time spent in line: " << "\t" << counters[AVERAGE_WAIT] << endl;
cout << "\t Average line length: " << "\t\t" << counters[AVERAGE_LINE] << endl;
cout << "\t Angry customers: " << "\t\t" << counters[ANGRY_CUSTOMERS] << endl;
cout << endl;
}
return 0;
}
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