RosettaCodeData/Task/Tree-from-nesting-levels/Raku/tree-from-nesting-levels-2....

26 lines
761 B
Raku

sub to_tree_recursive ( @list, $index is copy, $depth ) {
my @so_far = gather while $index <= @list.end {
my $t = @list[$index];
given $t <=> $depth {
when Order::Same {
take $t;
}
when Order::More {
( $index, my $n1 ) = to_tree_recursive( @list, $index, $depth+1 );
take $n1;
}
when Order::Less {
$index--;
last;
}
}
$index++;
}
my $i = ($depth > 1) ?? $index !! -1;
return $i, @so_far;
}
my @tests = (), (1, 2, 4), (3, 1, 3, 1), (1, 2, 3, 1), (3, 2, 1, 3), (3, 3, 3, 1, 1, 3, 3, 3);
say .Str.fmt( '%15s => ' ), to_tree_recursive( $_, 0, 1 ).[1] for @tests;