diff options
| -rw-r--r-- | challenge-069/colin-crain/perl/ch-1.pl | 59 |
1 files changed, 26 insertions, 33 deletions
diff --git a/challenge-069/colin-crain/perl/ch-1.pl b/challenge-069/colin-crain/perl/ch-1.pl index c1a3c8d434..ef6497300d 100644 --- a/challenge-069/colin-crain/perl/ch-1.pl +++ b/challenge-069/colin-crain/perl/ch-1.pl @@ -28,65 +28,58 @@ use feature ":5.26"; ## ## ## ## ## MAIN: -my ($A, $B) = @ARGV; ## low, high bounds -# ($A, $B) = (1000, 2000000000); +my ($A, $B) = @ARGV; ## low, high bounds + # the order is the length of the half number that is modified and -# joined to itself, with or without the pivot digit in the center. -# Thus a given order will generate numbers up to 2n+1 places long, or -# 10^(2n+1) The order is calculated to theoretically create numbers as -# large as B. As this value scales by magnitude 100, this number can -# be quite a bit larger, but will larger and we can guarantee none of -# the next larger order will be required. It serves as an upper bound +# joined to itself, with or without the pivot digit in the +# center. Thus a given order will generate numbers up to 2n+1 +# places long, or numbers up to but less than 10^(2n+1) The order +# is calculated to be large enough to create all numbers as large +# as B. As the maximum of the range scales by magnitude 100, the +# largest number created can still be quite a bit larger, but we +# can guarantee it will be large enough and also that none of the +# next larger order will be required. It serves as an upper bound # to the calculation space. my $order = int(length($B)/2); my @list = (0, 1, 6, 8, 9); my @center = (0, 1, 8); -my @num = @list[1..@list-1]; ## remove leading 0 -my @stereo = grep { $_ >= $A && $_ <= $B } @center; ## single digit cases +my @num = @list[1..@list-1]; ## remove leading 0 +my @stereo = @center; ## ensures trivial single digit cases -OUTER: for (0..$order-1) { - my @evens = my @odds = (); ## reset holding arrays +for (0..$order-1) { + my @evens = my @odds = (); ## reset holding arrays for my $left (@num) { my $right = reverse($left =~ tr/69/96/r); - - my $even = "$left$right"; - if ($even > $B) { - push @stereo, @evens, @odds; ## keeps things sorted - last OUTER; - } - push @evens, $even unless $even < $A; + push @evens, "$left$right"; for my $center (@center) { - my $odd = "$left$center$right"; - last if $odd > $B; - next if $odd < $A; - push @odds, $odd; + push @odds, "$left$center$right"; } } + push @stereo, @evens, @odds; ## keeps things sorted ## add another digit to the working list @num = map { my $c = $_; map "$c$_", @list } @num; } -# for ( @stereo ) { -# next if $_ < $A; -# last if $_ > $B; -# say $_; -# } - -say $_ for @stereo; - - +## output within the specified range +for ( @stereo ) { + next if $_ < $A; + last if $_ > $B; + say $_; +} ## ## ## ## ## SUBS: ## included because I wanted to write a regex to find these numbers, ## but an impractical method in the end. sub is_strobogrammatic { - $_[0] =~ m/^([16890]*)[180]?((??{reverse($1=~tr[69][96]r)}))$/ ? 1 : 0 + $_[0] =~ m/^([16890]+)[180]?((??{my $n=$1;$n=~tr[69][96];reverse($n)}))$/ + ? "$_[0] is strobogrammatic" + : "$_[0] is not strobogrammatic" } |