Roelof Wobben wrote
"I have to reread the file till the adding causes the same outcome as we
had already"
You have to process the *sequence of changes* repeatedly;
you DON't have to *reread the file*. Somebody already made this point.
Having read the changes into an array, you can iterate repeatedly over that
array.
to find the first repeated frequency given a sequence of changes
make an empty Set to hold the sums that have been seen so far.
set the frequency to 0.
loop forever
for each change in the changes
increment the frequency by the change.
if the frequency is in the set
return the frequency
otherwise add the frequency to the set.
partTwo: aFileName
Transcript print: (self firstRepeatedFrequency: (self changesFrom:
aFileName)); cr; flush.
On Mon, 3 Dec 2018 at 19:31, Roelof Wobben <r.wob...@home.nl> wrote:
> Thanks,
>
> For the second I have to take a good look.
>
> I have to reread the file till the adding causes the same outcome as we
> had already
>
> so for example if we have the sequence :
>
> +3, +3, +4, -2, -4
>
> it has as outcome :
>
> 3 6 10 8 4
>
> so no outcome is there a second time so we repeat the sequence
>
>
> 7 10
>
> the 10 shows up a second time so there we have our answer.
>
>
> Roelof
>
>
>
> Op 3-12-2018 om 03:45 schreef Richard O'Keefe:
>
> The key question is "what do you mean by improve"?
> I'd start by asking "what are you doing that you will still have to do in
> part 2, and what won't you do?" So looking at part 2, you will want to
> convert the lines to integers, and
> input := Array streamContents: [:lines |
> 'input.txt' asFileReference readStreamDo: [:in |
> [in atEnd] whileFalse: [lines nextPut: in nextLine asInteger]]].
> gives you a chunk of code you can use in both parts. So you might
> want to have
>
> Day1
> changesFrom: aFileName
> ^Array streamContents: [:changes |
> aFileName asFileReference readStreamDo: [:in |
> [in atEnd] whileFalse: [changes nextPut: in nextLine asInteger]]]
> partOne: aFileName
> ^(self changesFrom: aFileName) sum
> partTwo: aFileName
> ...
> The file name should not be wired in because you want some test files.
>
>
>
>
