A breadth-first search that uses disk files to avoid memory exhaustion. Each candidate sequence is encoded at one character per name, so to avoid reuse of names we merely have to make sure there are no repeat characters in our encoded string. (The encoding starts at ASCII space for the first name, so newline is not among the encoded characters.)
my @names = <
audino bagon baltoy banette bidoof braviary bronzor carracosta charmeleon
cresselia croagunk darmanitan deino emboar emolga exeggcute gabite
girafarig gulpin haxorus heatmor heatran ivysaur jellicent jumpluff kangaskhan
kricketune landorus ledyba loudred lumineon lunatone machamp magnezone mamoswine
nosepass petilil pidgeotto pikachu pinsir poliwrath poochyena porygon2
porygonz registeel relicanth remoraid rufflet sableye scolipede scrafty seaking
sealeo silcoon simisear snivy snorlax spoink starly tirtouga trapinch treecko
tyrogue vigoroth vulpix wailord wartortle whismur wingull yamask
>;
my @last = @names.map: {.substr(*-1,1).ord }
my @succs = [] xx 128;
for @names.kv -> $i, $name {
my $ix = $name.ord; # $name.substr(0,1).ord
push @succs[$ix], $i;
}
my $OUT = open "llfl.new", :w orelse .die;
$OUT.print: chr($_ + 32),"\n" for 0 ..^ @names;
close $OUT;
my $new = +@names;
my $len = 1;
while $new {
say "Length { $len++ }: $new candidates";
shell 'mv llfl.new llfl.known';
my $IN = open "llfl.known" orelse .die;
my $OUT = open "llfl.new", :w orelse .die;
$new = 0;
loop {
my $cand = $IN.get // last;
for @succs[@last[$cand.ord - 32]][] -> $i {
my $ic = chr($i + 32);
next if $cand ~~ /$ic/;
$OUT.print: $ic,$cand,"\n";
$new++;
}
}
$IN.close;
$OUT.close;
}
my $IN = open "llfl.known" orelse .die;
my $eg = $IN.lines.pick;
say "Length of longest: ", $eg.chars;
say join ' ', $eg.ords.reverse.map: { @names[$_ - 32] }