frogwalk.cc  From Astrachan, pp 311
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#include <iostream.h>
#include "dice.h"
#include "prompt.h"

// simulate one-dimensional random walk
// Owen Astrachan, 8/13/94

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

    int position = 0;         // "frog" starts at position 0
    Dice die(2);              // used for "coin flipping"
    int k;
    for(k=0; k < numSteps; k++)
    {
        switch (die.Roll())
        {
          case 1:
            position += 1;    // step to the right
            break;
          case 2:
            position -= 1;    // step to the left
            break;
        }
    }
    cout << "final position = " << position << endl;
    return 0;
}