in reply to Re: (corrections) Re: Answer: Efficient access to sparse lists?
in thread Efficient access to sparse lists?

Ah, now I finally understand what you want. (:

You need a more complex data structure. You can wrap a nice interface around it if you like, but I'll leave that part up to you (or others).

I think you've found a reason to implement a linked list in Perl (normally you don't need such things in Perl). I went with a circular, doubly-linked list for ease of implementation (where "turn 0" is a dummy turn used to find the first and last turns):

my %turn= ( 0=>{Next=>5,Prev=>53}, 5=>{Turn=>"turn 0",Prev=>0,Next=>28}, 28=>{Turn=>"turn 28",Prev=>5,Next=>53}, 53=>{Turn=>"turn 53",Prev=>28,Next=>0}, ); sub pushTurn { my( $num, $turn )= @_; my $last= $turn{0}{Prev}; $turn{$num}= {Turn=>$turn,Prev=>$last,Next=>0}; $turn{0}{Prev}= $num; $turn{$last}{Next}= $num; } sub deleTurn { my( $num )= @_; my( $prev, $next )= @{ $turn{$num} }{qw( Prev Next )}; $turn{$prev}{Next}= $next; $turn{$next}{Prev}= $prev; delete $turn{$num}; }

I hope that is close enough to correct that you can get an implementation working. {-:

Use:

my %turn= ( 0=>{Next=>0,Prev=>0} );
to bootstrap the data structure.

        - tye (but my friends call me "Tye")