I didn't bother with sparse arrays for aoc 12, but used what I think
is a similar approach:
id2num=:_ ". ] -. -.&(":i.10)
id2con=:3 :0
nodes=: {.@id2num;._2 y
assert. (-: i.@#) nodes
nodes&e.@id2num;._2 y
)
tc=: (+. +./ .*~)^:_
aoc12a=:#@I.@{.@tc@id2con
aoc12b=:#@~.@:I.@tc@id2con
Good luck,
--
Raul
On Tue, Dec 12, 2017 at 11:40 PM, Jimmy Gauvin <[email protected]> wrote:
> HI all,
>
> this AOC challenge is great for trying out J cool features, like sparse
> arrays which I haven't used to date.
>
> For part 1 I decided to try transitive closure on a sparse matrix.
>
> Initializing the sparse array went ok but the transitive closure produced a
> big bang and J just died on me, 8-(
>
> So I went for a brute force approach : visiting all predecessors to node.
>
> d12=: <&;:;.(_2) 1!:1 <'/day12inp'
> d12c=:".&; each 4}. each d12
>
> nodto =: 3 : 0
> ~. y , ; y { d12c
> )
>
> $nodto ^:_ (0)
> 169
>
>
> There must be a nicer way to write this code.
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