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#include <iostream>
using namespace std;

#include <ctime>
#include <cstdlib>
#include <iomanip>

void walk(int, int, float, float&, float&); // prototype

int main()
{
   int start, walks;
   float pub_prob, at_pub, avg_blks;

   cout << "Enter probability of going towards the pub: ";
   cin >> pub_prob;

   cout <<  "Enter number of walks: ";
   cin >> walks;

   cout << "Enter number of the starting block (2 - 7): ";
   cin >> start;

   srand( time(NULL)); // seed

   // call function walk

   walk(start, walks, pub_prob, at_pub, avg_blks);

   // display results
 

   cout << setiosflags(ios::fixed) << setprecision(2);

   cout << "Starting at block " << start
        << "\nSafe at home " << (100. - at_pub) << " per cent of walks"
        << "\nBack at pub  " << at_pub << " per cent of walks"
        << "\nAverage number of blocks walked " << avg_blks
        << endl << endl;

}

void walk(int start, int walks, float p, float& at_pub, float& avg_blks)
{
   int i, block, pub = 0, num_blks = 0;
   float rannum;

   for (i = 1; i <= walks; i++)
   {
      block = start; // initialize block

      while(block > 1 && block < 8)
      {
          rannum = static_cast< float >( rand() ) / RAND_MAX; // get random #

          num_blks++; // increment number of blocks walked

          if ( rannum < p )
            block = block - 1; // move toward pub

          else
            block = block + 1; // move toward home

          // cout << "random = " << rannum << "   block = " << block << endl;

      } // end while loop

      if (block == 1)
        pub++;  // at the pub
 

   } // end for loop

   // calculate statistics

   at_pub = 100. * static_cast< float >( pub ) / walks;
   avg_blks = static_cast< float >( num_blks) / walks;
}

% g++ walk2.cpp
% a.out
Enter probability of going towards the pub: .666
Enter number of walks: 500
Enter number of the starting block (2 - 7): 4
Starting at block 4
Safe at home 5.00 per cent of walks
Back at pub  95.00 per cent of walks