Birthday Chances

[YuckFoo]

On average, how large a group is required for two people to have the same birthday? I remembered the answer was lower than I expected, but I forgot what the answer was.

Stuff like that bothers me. I suck at probability theory so often use Monte Carlo method for solutions.

So who cares? If you are in a room with this number of people with nothing to do (ie network is down), bet them all a buck that two people in the room share a birthday. Then send me a buck.

BuckFoo

#!/usr/bin/perl

   use strict;

   my $TRIALS = 1024;
   my $total;

   for (1..$TRIALS) { $total += trial(); }

   $total /= $TRIALS;
   print "$total\n";

sub trial {

   my (%days, $i);

   while (++$i) {
      if ($days{int(rand(365))}++) { return $i; }
   }
}