On Fri, 9 Nov 2018 at 15:25, Roelof Wobben <r.wob...@home.nl> wrote:
> Hello,
>
> I try to solve a adventofcode challenge where I must find out when santa
> is first at the basement. the floor is there -1.
> So I thought I use a while loop like this :
>
> santaFloorOnBasement
> "calculates which step take Santa to the basement"
> | index|
> index := 1.
> ??? when: (floor >=0 ) do:
> [ floor := (input at: index = '(' )
> ifTrue: [ floor + 1 ]
> ifFalse: [ floor - 1 ].
> index := index + 1 ].
>
> but I cannot find out what must be instead of the ??
>
I've never used #when:do: so I can't comment on that.
I'd be using #whileTrue: which looks like this... [ condition block ]
whileTrue: [ action block ]
<<< ??? when: (floor >=0 ) do:
>>> [floor>=0] whileTrue:
For further examples review the "senders" of #whileTrue:
i.e. highlight then press <CTRL-N> on MS Windows
> index is the index of the string which has to start with a 1.
> floor and input are both instance variables. floor contains the current
> floor and input the input of the challenge.
>
> Can someone help me figure this out so the next time I can do this on my
> own.
>
btw you have a problem here...
floor := (input at: index = '(' )
Its not doing what you think and you'll get "Error: only integers should be
used as indices"
Consider you that two messages are being sent:
* the keyword message... #at:
* the binary message.... #=
Homework :)... what is the third type of message and the evaluation
priority of all three.
Homework 2... Review the "implementors" of message #=
<CTRL-M> on MS Windows
cheers -ben
P.S. As it current stands, you'll get a "SubscriptOutOfBounds" error if
the input ends before Santa gets to the basement.
An exercise, fix that using the existing loop.
Then consider using an iterator...
input do: [ :bracket |
(bracket = $( ) ifTrue: [ floor := floor + 1 ] .
(bracket = $( ) ifTrue: [ floor := floor + 1 ] ].
and maybe something else for you to experiment with...
movement := Dictionary new.
movement at: $( put: 1.
movement at: $) put: -1.
input do: [ :char | floor := floor + (movement at: char ifAbsent: [0])
].
cheers -ben
