TRIE solution. 50 seconds too slow though

rosalind/trie-grondilu.pl

@@ -0,0 +1,54 @@
+use v6;
+
+my Int $node = 1;
+
+sub trie(@string is copy, $root = $node) {
+    @string .= grep: *.chars;
+    return {} if not @string;
+    hash gather for @string.classify(*.substr: 0, 1).kv -> $k, $v {
+        my @value = map *.substr(1), grep *.chars > 1, $v[];
+	say "$root {++$node} $k";
+	take $k => &?ROUTINE( @value, $node ) if @value;
+    }
+}
+
+trie <ATAGA ATC GAT>;
+
+=END
+use strict;
+use warnings;
+no warnings qw(recursion);
+
+my $node = 1;
+
+sub classify {
+    my $f = shift;
+    my %classif;
+    for (@_) {
+        $classif{$f->($_)} //= [];
+        push $classif{$f->($_)}, $_;
+    }
+    \%classif;
+}
+
+sub trie {
+    my @string = @{shift()};
+    my $root = shift // $node;
+    return +{} if not @string;
+    my %trie;
+    my %classify = %{ classify sub { substr shift, 0, 1 }, @string };
+    for my $key (keys %classify) {
+        my @value = map { substr $_, 1 } grep { length > 1 } @{$classify{$key}};
+        printf "%i %i %s\n", $root, ++$node, $key;
+        $trie{$key} = trie( [ @value ], $node ) if @value;
+    }
+    return \%trie;
+}
+
+trie [ map { chomp; $_ } <> ];
+__END__
+trie [ qw(ATAGA ATC GAT) ];
+
+__END__
+
+# vim: ft=perl6