frogwalk3.cc  From Astrachan pp 327-328
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#include <iostream.h>
#include <fstream.h>

#include "prompt.h"
#include "walko.cc"
#include "observer.h"

// simulate two random walkers at once
// Owen Astrachan, 6/29/96
//
// uses a WalkObserver to monitor each of the random walkers

WalkObserver::WalkObserver(const string & filename)
{
    myOutputStream.open(filename);
}

void WalkObserver::Update(int step, int position)
{
    myOutputStream << step << " " << position << endl;
}

int main()
{
    int numSteps = PromptRange("enter # steps",0,1000000);

    WalkObserver frogObserver("frog.out");
    WalkObserver toadObserver("toad.out");
    RandomWalkO frog(frogObserver,numSteps);  // define two random walkers
    RandomWalkO toad(toadObserver,numSteps);  
    int samePadCount = 0;                    // # times at same location
    
    frog.First();
    toad.First();

    while (! frog.IsDone() && ! toad.IsDone())
    {
        if (frog.GetPosition() == toad.GetPosition())
        {
            samePadCount++;
        }
        frog.Next();
        toad.Next();
    }
    cout << "frog position = " << frog.GetPosition() << endl;
    cout << "toad position = " << toad.GetPosition() << endl;
    cout << "# times at same location = " << samePadCount << endl;
    return 0;
}