Here's my AoC Day2 solution. I first converted the course into a matrix with
one column each for moves forward, moves up, and moves down. I then used matrix
multiplications and running sums to get the horizontal movement, aim, and depth.
Mike
cutspace =: [: <;._1 ' '&,
parse =: {{)m
course =. cutspace&> cutLF y
directions =. {."1 course
distances =. ". > {:"1 course
distances *"0 1 directions ="0 1 'forward';'down';'up'
}}
follow1 =: {{)m
horizontal =. +/\ y +/ .* 1 0 0
depth =. +/\ y +/ .* 0 1 _1
({: horizontal) ; ({: depth) ; horizontal *&{: depth
}}
follow2 =: {{)m
horizontal =. +/\ y +/ .* 1 0 0
aim =. +/\ y +/ .* 0 1 _1
depth =. +/\ aim * y +/ .* 1 0 0
({: horizontal) ; ({: aim) ; ({: depth) ; horizontal *&{: depth
}}
--
Michael P. Manti
[email protected]
> On Dec 23, 2021, at 02:41, Skip Cave <[email protected]> wrote:
>
> Here's my AoC Day 2 solution: https://adventofcode.com/2021/day/2
> this problem seemed perfect for running sums (+/\)
>
> n=.'b' freads 'depth2.txt' NB. Read in File
> a=.'forward';'up';'down'
> s=.;".ea{:ea n NB. Get numeric values (ea = each)
> t=.+./@E.&.> NB. string match mark each.
> m=.s*"1[1 _1 1*>((0{a)t n),((1{a)t n),:((2{a)t n) NB. Set up for running
> sums
> {:+/\+/1 2{m NB. Get running depth sums
> 820
> {:+/\0{m NB. Get running distance sums.
> 2018
>
> 820*2018
> 1654760 NB. Answer
>
> Skip Cave
> Cave Consulting LLC
>
>
>> On Wed, Dec 22, 2021 at 2:59 PM 'Michael Day' via Programming <
>> [email protected]> wrote:
>>
>> Apologies - more chat than programming, but: fwiw, for part 1, I just
>> defined simple
>> one-liner functions "forward" etc which worked ok. For part 2, they
>> needed redefining, and,
>> yes, I used direct defs; nothing as sophisticated as fold!
>>
>> I've done days 1-17, mostly straightforward, some very fiddly.
>>
>> But I'm stuck at 18, which is v complicated in its explanation. I
>> started with boxes in J,
>> but found navigation hard - I haven't used nested structures much in J -
>> so resorted to
>> working on the untranslated rows, using ;: to separate the symbols &
>> numbers, but
>> couldn't get all the examples to reproduce the stated results! So
>> I've wasted yet more time
>> learning - or relearning - how to deal with nested arrays in Dyalog APL
>> and remembering how
>> to use John Scholes' dfns. Managed to "reduce" the "addition" of the
>> first pair of snailnumbers,
>> but reducing the "addition" of the third line defeats me. I suppose I'm
>> sometimes inserting
>> some result at the wrong depth.
>>
>> I've spent so much time on that that I'll probably give up the rest!
>>
>> Cheers,
>>
>> Mike
>>
>>
>>> On 22/12/2021 14:59, Raul Miller wrote:
>>> (responding to
>> http://jsoftware.com/pipermail/programming/2021-December/059436.html#)
>>>
>>> I am not sure that I thought this example out well enough for it to be
>>> good on an examples page.
>>>
>>> For instance, after thinking about it for just a few minutes, I realized
>> that
>>>
>>> b2fold=: 0 0 0&(}.F..{{
>>> 'dH0 dA0 N'=. x
>>> 'A H D'=. y
>>> dA=: N*dA0
>>> dH=: N*dH0
>>> dD=: A*dH
>>> y+dA,dH,dD
>>> }})
>>>
>>> b2=: {{*/b2fold y}}
>>>
>>> would have been clearer.
>>>
>>> (Originally I was using ]F.. and commenting that I needed to drop the
>>> first item of the result. But isn't it clearer to include that drop
>>> mechanism with the fold implementation?)
>>>
>>> But (and this is worse): this particular example lacks utility, which
>>> means that it's not going to be very interesting for anyone.
>>>
>>> Other opportunities will arise, though. And I think that your concept
>>> of linked example pages is a good one and worth following up on.
>>>
>>> Thanks,
>>>
>>
>>
>> --
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