# include <cstdlib>
# include <iostream>
# include <ctime>

using namespace std;

int main ( )
//
//  DUEL_MANY carries out the duel many times, and prints the estimated
//  probabilities of survival.
//
{
  int i, n, one_wins, seed, two_wins, winner;
  int duel_once ( );

  cout << "Enter number of times the duel will be fought.\n";
  cin >> n;

  seed = time ( 0 );
  srand48 ( seed );
  one_wins = 0;
  two_wins = 0;

  for ( i = 1; i <= n; i++ )
  {
    winner = duel_once ( );
    if ( winner == 1 )
    {
      one_wins = one_wins + 1;
    }
    else
    {
      two_wins = two_wins + 1;
    }
  }
  cout << "\n";
  cout << "The duel was fought " << n << " times.\n";
  cout << "Player 1 has a winning probability of " 
       << ( double ) one_wins / double ( n ) << "\n";
  cout << "Player 2 has a winning probability of " 
       << ( double ) two_wins / double ( n ) << "\n";
  return 0;
}
int duel_once ( )
//
//  DUEL_ONCE simulates a duel between players of equal accuracy.
//  The players alternate until one has been hit.
//  For this situation, with accuracies of 1/2, the first player has a 2/3 
//  chance of surviving, simply by going first.
//
{
  int shot, winner;
//
//  Initialize the random number generator.
//
  winner = 0;
  shot = 0;
  
  while ( winner == 0 )
  {
    shot = shot + 1;
    if ( drand48 ( ) <= 0.5 )
    {
      winner = 1;
      break;
    }
    shot = shot + 1;
    if ( drand48 ( ) <= 0.5 )
    {
      winner = 2;
      break;
    }
  }
  cout << "Duel was won by " << winner << " after " << shot << " shots.\n";
  return winner;
}