#!/usr/bin/perl
use strict;
use warnings;

my $runs = 10000;
my $luck = 0;

for(1..$runs) {
    # Generate the lucky parcel
    my $hasxp = int(rand(3)) + 1;
    
    # Now, select one parcel from the 3 at random
    my $parcel = int(rand(3)) + 1;
    
    # We stick to our decision, so we don't care
    # what happens to the other parcels
    
    # Now, see if we were lucky:
    if($parcel == $hasxp) {
        $luck++;
    }
}

# print out the end result in percent
print "You were lucky " . int($luck * 100 / $runs) . "% of the time sticking to your initial decision.\n";

##</code><code>##

#!/usr/bin/perl
use strict;
use warnings;

my $runs = 10000;
my $luck = 0;

for(1..$runs) {
    # Generate the lucky parcel
    my $hasxp = int(rand(3)) + 1;
    
    # Now, select one parcel from the 3 at random
    my $parcel = int(rand(3)) + 1;
    
    # ** Now, the computer removes one of the empty parcels and we select the remaining one **
    
    # First, make a "list" of parcels and remove the one the user is holding
    my $all = '123';
    $all =~ s/$parcel//;
    
    # Now, randomly select one of the remaining ones and check
    # if it's empty and *not* currently held by the user
    while(1) {
        my $gone = int(rand(3)) + 1;
        
        # Check if we can remove that one from the list
        next if($gone == $parcel); # can't remove, held by the user
        next if($gone == $hasxp); # don't remove the lucky one
        
        $all =~ s/$gone//; # Remove it and finish
        last;
    }
    
    # Given that we eliminated two parcels from a list of three,
    # there is one left the user *can* select, so let's do it
    $parcel = $all;
    
    # Now, see if we were lucky:
    if($parcel == $hasxp) {
        $luck++;
    }
}

# print out the end result in percent
print "You were lucky " . int($luck * 100 / $runs) . "% of the time changing your decision.\n";

##</code><code>##

You were lucky 33% of the time sticking to your initial decision.
You were lucky 66% of the time changing your decision.