#!/usr/bin/perl

use Time::HiRes qw(gettimeofday tv_interval);
use List::Util 'shuffle'; # perlfaq4
 
use warnings;
use strict;

my @ups = ('0') x 10;

# four suits are added to a deck and then shuffled
my @deck = shuffle(('A' .. 'M') x 4);

#print "@deck\n"; exit 0;

print "\n";
my $t0 = gettimeofday;

$ups[0] = shift @deck;
eval
{
my $done = 0;
while (!$done)
{
	print "@ups\n";

	$done = 1;
	scan:
	for (my $j=1;$j<10;$j++)
	{
		$ups[$j] eq '0' and $ups[$j] = (shift @deck or die);
		for (my $k=0;$k<$j;$k++)
		{
			if ( $ups[$j] eq $ups[$k] )
			{
				$ups[$j] = (shift @deck or die);
				$ups[$k] = (shift @deck or die);
				$done = 0;
				last scan;
			}
		}
	}
}
};

print "\n@ups\tExit row\n";

my $usec = sprintf("%.2f", (gettimeofday - $t0) * 10**6);
print "\n".(52-@deck)." passes in $usec microseconds. ";
print !@deck
	? "Succeeded in consuming the entire deck.\n\n"
	: "Failed to consume the entire deck.\n\n";