use strict;
use warnings;
use Data::Dumper;

my @input = (
	'foo:'   => 1,
	'bar:'   => 2,
	'baz',  # no colon, so value is "1"
	'quux:'  => 3,
);

my %output;
while (@input)
{
	my $key = shift @input;
	
	if ($key =~ /\A(.+):\z/)
	{
		$output{$1} = shift @input;
	}
	else
	{
		$output{$key} = 1;
	}
}

print Dumper \%output;