Data commit

Task/Straddling-checkerboard/Perl/straddling-checkerboard.pl

@@ -0,0 +1,51 @@
+use strict;
+use warnings;
+use feature 'say';
+use List::Util <min max>;
+
+my(%encode,%decode,@table);
+
+sub build {
+    my($u,$v,$alphabet) = @_;
+    my(@flat_board,%p2c,%c2p);
+    my $numeric_escape = '/';
+
+    @flat_board = split '', uc $alphabet;
+    splice @flat_board, min($u,$v), 0, undef;
+    splice @flat_board, max($u,$v), 0, undef;
+
+    push @table, [' ', 0..9];
+    push @table, [' ', map { defined $_ ? $_ : ' '} @flat_board[ 0 ..  9] ];
+    push @table, [$u,  @flat_board[10 .. 19]];
+    push @table, [$v,  @flat_board[20 .. 29]];
+
+    my @nums = my @order = 0..9;
+    push @nums, (map { +"$u$_" } @order), map { +"$v$_" } @order;
+
+    @c2p{@nums} = @flat_board;
+    for (keys %c2p) { delete $c2p{$_} unless defined $c2p{$_} }
+    @p2c{values %c2p} = keys %c2p;
+    $p2c{$_} = $p2c{$numeric_escape} . $_ for 0..9;
+    while (my ($k, $v) = each %p2c) {
+        $encode{$k} = $v;
+        $decode{$v} = $k unless $k eq $numeric_escape;
+    }
+}
+
+sub decode {
+    my($string) = @_;
+    my $keys = join '|', keys %decode;
+    $string =~ s/($keys)/$decode{$1}/gr;
+}
+
+sub encode {
+    my($string) = uc shift;
+    $string =~ s#(.)#$encode{$1} // $encode{'.'}#ger;
+}
+
+my $sc = build(3, 7, 'HOLMESRTABCDFGIJKNPQUVWXYZ./');
+say join  ' ', @$_ for @table;
+say '';
+say 'Original: ', my $original = 'One night-it was on the twentieth of March, 1888-I was returning';
+say 'Encoded:  ', my $en = encode($original);
+say 'Decoded:  ', decode($en);