# Advent of Code 2022 **URL:** \ **Category:** Announcements\ **Created:** [November 27, 2022, 11:01am UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816 "2022-11-27T11:01:09Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![vmagnin](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/vmagnin/32/28_2.png) [@vmagnin](https://fortran-lang.discourse.group/u/vmagnin)\ **Post date:** [November 27, 2022, 11:01am UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816/1 "2022-11-27T11:01:09Z")
> _Advent of Code_ is an [Advent calendar](https://en.wikipedia.org/wiki/Advent_calendar) of small programming puzzles for a variety of skill sets and skill levels that can be solved in [any](https://github.com/search?q=advent+of+code) programming language you like. > The first puzzles will unlock on December 1st at midnight EST (UTC-5). See you then! [https://adventofcode.com/](https://adventofcode.com/) ---
**Author:** ![awvwgk](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/awvwgk/32/154_2.png) [@awvwgk](https://fortran-lang.discourse.group/u/awvwgk)\ **Post date:** [November 27, 2022, 12:35pm UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816/2 "2022-11-27T12:35:53Z")
We should create a leaderboard for Fortran-lang again. Or we can use one of the previous years: - [Leaderboard - Advent of Code 2021](https://adventofcode.com/2021/leaderboard/private/view/1510956) - [Leaderboard - Advent of Code 2020](https://adventofcode.com/2020/leaderboard/private/view/1058222) ---
**Author:** ![Aurelius\_Nero](https://avatars.discourse-cdn.com/v4/letter/a/a87d85/32.png) [@Aurelius\_Nero](https://fortran-lang.discourse.group/u/Aurelius_Nero)\ **Post date:** [November 27, 2022, 12:53pm UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816/3 "2022-11-27T12:53:59Z")
nahh, we need one for 2022 ---
**Author:** ![sblionel](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/sblionel/32/853_2.png) [@sblionel](https://fortran-lang.discourse.group/u/sblionel)\ **Post date:** [November 27, 2022, 5:04pm UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816/4 "2022-11-27T17:04:03Z")
I’m looking forward to participating in this again. ---
**Author:** ![Carltoffel](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/carltoffel/32/1680_2.png) [@Carltoffel](https://fortran-lang.discourse.group/u/Carltoffel)\ **Post date:** [November 28, 2022, 3:13pm UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816/5 "2022-11-28T15:13:33Z")
Let’s use the same leaderboard as last year. Every year gets a separate score, and you can still see the scores from previous years. The leaderboard code is `1510956-4380811b` and you have to enter it [here](https://adventofcode.com/2022/leaderboard/private) (you need to be logged in, otherwise you’ll get redirected elsewhere). ---
**Author:** ![Beliavsky](https://avatars.discourse-cdn.com/v4/letter/b/ba8739/32.png) [@Beliavsky](https://fortran-lang.discourse.group/u/Beliavsky)\ **Post date:** [November 28, 2022, 4:37pm UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816/6 "2022-11-28T16:37:20Z")
One can find Fortran solutions for the 2021 edition on GitHub with [Search · aoc-2021-in-fortran · GitHub](https://github.com/search?q=aoc-2021-in-fortran). I suggest that the analogous topic be used for the 2022 edition. ---
**Author:** ![Carltoffel](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/carltoffel/32/1680_2.png) [@Carltoffel](https://fortran-lang.discourse.group/u/Carltoffel)\ **Post date:** [December 1, 2022, 2:45pm UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816/7 "2022-12-01T14:45:53Z")
While overengineering today’s AOC tasks, I stumbled into some limitations of Fortran (or maybe limitations of my Fortran skills?). The task is to parse a list of integers, sum up each group and find the maximum. The way I tried to do it was a kind of parser. The general structure of function calls looks like this: > **call graph** > > ```auto > max_calories > -> get_next_sum > -> get_next_integer > -> get_next_line > -> intrinsic read > > ``` The first problem I had was the fact, that there is no straightforward way of handling exceptions. If the innermost `read` hits `eof`, this information has somehow to be handed back to the outermost function. I tried to do this by returning `allocatable` integers, where an unallocated integer would have meant, the file has reached `eof`. Unfortunately, Fortran cannot return this kind of information, so I had to add an `logical :: eof` to my reader `class`. Similar to this, I needed a way to handle empty lines. In this case, I can simply return `0`, but I’m asking myself if there is a better solution, especially when the parser logic would be more complex. Would I require an `eof` equivalent for each level of abstraction/function (or a more general status variable)? Another problem I found is inheritance of class constructors. I use two classes, a task specific “calories parser” and a more general file reader (which can read integers). The file reader opens the file and stores the file unit in the constructor function. The calories parser extends the file reader with the `next_calories` method, which basically returns the next sum of contiguous integer lines. Now if I want to create a new calories parser, I want to use the constructor of the file reader, but I didn’t manage to find a way that made me happy. My last approach is a member subroutine in the file reader, which acts as constructor and can be called by another constructor function, which has to be defined for each child class. > **constructor diagram** > > ```auto > type(calories_reader_t) :: cr > cr = calories_reader_t(filename) > -> interface calories_reader_t > -> calories_reader_constructor > -> call cr%constructor(filename) > -> file_reader%constructor(filename) > > ``` > **[GitHub - Carltoffel/aoc22\_fortran](https://github.com/Carltoffel/aoc22_fortran)** > > Contribute to Carltoffel/aoc22\_fortran development by creating an account on GitHub. Funfact: In contrast to this highly overengineered Fortran solution, you can solve the puzzle with one line of “shell” or Python: > **Shell and Python one-liner** > > ```auto > cat input.txt | tr '\n' '+' | sed 's/++/\n/g;s/+$/\n/' | bc | sort --numeric-sort --reverse | head -3 | tr '\n' '+' | sed 's/+$/\n/' | bc > > ``` > > ```auto > sum(sorted(map(lambda _:eval(_.replace('\n','+')),open("input.txt").read()[:-1].split(2*'\n')))[-3:]) > > ``` ---
**Author:** ![sblionel](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/sblionel/32/853_2.png) [@sblionel](https://fortran-lang.discourse.group/u/sblionel)\ **Post date:** [December 1, 2022, 6:33pm UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816/8 "2022-12-01T18:33:27Z")
That does seem like overengineering, but that can be fun. I started out simple. > **[GitHub - sblionel/AOC2022-in-Fortran](https://github.com/sblionel/AOC2022-in-Fortran)** > > Contribute to sblionel/AOC2022-in-Fortran development by creating an account on GitHub. ---
**Author:** ![ofmla](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/ofmla/32/3320_2.png) [@ofmla](https://fortran-lang.discourse.group/u/ofmla)\ **Post date:** [December 1, 2022, 6:49pm UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816/9 "2022-12-01T18:49:49Z")
I wrote a simple program that seem to do the work ```auto program day1 implicit none integer :: ios integer, parameter :: read_unit = 99 integer, allocatable :: numbers(:) character(len=200) :: line integer :: n, i, count, number open(unit=read_unit, file='calories.txt', iostat=ios) if ( ios /= 0 ) stop "Error opening file data.dat" n = 0 do read(read_unit, '(A)', iostat=ios) line if (ios /= 0) exit if (len(trim(line)) == 0 ) n = n + 1 end do print*, "File contains ", n, "blanks line" allocate(numbers(n+1)) rewind(read_unit) count = 0 i = 0 do read(read_unit, '(A)', iostat=ios) line if (ios /= 0) exit if (len(trim(line)) == 0 ) then i = i + 1 numbers(i) = count count = 0 else read (line,'(I10)') number count = count + number endif end do numbers(n+1) = count print*, "highest calories value carried by an elf is: ", maxval(numbers) close(read_unit) end program day1 ``` ---
**Author:** ![awvwgk](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/awvwgk/32/154_2.png) [@awvwgk](https://fortran-lang.discourse.group/u/awvwgk)\ **Post date:** [December 1, 2022, 7:00pm UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816/10 "2022-12-01T19:00:13Z")
> [@Carltoffel](#): > > Funfact: In contrast to this highly overengineered Fortran solution, you can solve the puzzle with one line of “shell” or Python: I am probably going to do most of them in awk again, much fun. Maybe I’ll also do some in Fortran. > **[GitHub - awvwgk/AoC-2022: Advent of Code 2022 in many languages, questionable...](https://github.com/awvwgk/AoC-2022)** > > Advent of Code 2022 in many languages, questionable code quality is guaranteed - GitHub - awvwgk/AoC-2022: Advent of Code 2022 in many languages, questionable code quality is guaranteed ---
**Author:** ![RonShepard](https://avatars.discourse-cdn.com/v4/letter/r/a3d4f5/32.png) [@RonShepard](https://fortran-lang.discourse.group/u/RonShepard)\ **Post date:** [December 1, 2022, 7:56pm UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816/11 "2022-12-01T19:56:10Z")
> [@ofmla](#): > > `len(trim(line))` This is an expensive way to look for a blank line. The `trim()` function must first scan the line to look for the last nonspace character, then allocate memory, then copy characters into that new memory. Then the `len()` function looks to see the length of that new character string. The `len_trim()` function just does the first step, it scans the line and returns the integer result. Of course, a compiler might recognize the dead code in the` len(trim(line))` expression and do the right things anyway, maybe with some level of optimization being specified, but why depend on that when `len_trim()` is right there? However, there might be other ways to answer the question, and I’m not sure which is best. The expression `line==' '`, returns `.true.` for a blank line. Character string comparisons in fortran test the leading characters for equality, in this case a single space, and then ensure that the rest of the line has only trailing spaces. That might be more efficient since the compiler can do those tests on multiple bytes at a time. Also, that expression arguably looks simpler to a human reading the code. That comparison also works with a zero-length string, `''`, but I usually compare to a single space out of habit (f77 did not allow zero-length strings). The best solution to this would be for the read statement to tell you how many characters it read, so you could limit the subsequent comparisons to just those characters. This was a feature of 1970s-era DEC VAX I/O, but unfortunately it never made it into any fortran standard. ---
**Author:** ![everythingfunctional](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/everythingfunctional/32/176_2.png) [@everythingfunctional](https://fortran-lang.discourse.group/u/everythingfunctional)\ **Post date:** [December 1, 2022, 9:01pm UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816/12 "2022-12-01T21:01:25Z")
> [@RonShepard](#): > > The best solution to this would be for the read statement to tell you how many characters it read, so you could limit the subsequent comparisons to just those characters. This was a feature of 1970s-era DEC VAX I/O, but unfortunately it never made it into any fortran standard. Actually, it did. > The SIZE= specifier in an input statement causes the variable specified to become defined with the count of the characters transferred from the file by data edit descriptors during the input operation. Blanks inserted as padding are not counted. ---
**Author:** ![FedericoPerini](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/federicoperini/32/1750_2.png) [@FedericoPerini](https://fortran-lang.discourse.group/u/FedericoPerini)\ **Post date:** [December 1, 2022, 9:05pm UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816/13 "2022-12-01T21:05:00Z")
I took the challenge of doing this with the shortest possible code. I’ve just found the shortest way of dealing with blanks is: ```fortran read(iunit,'(i10)',blank='ZERO',iostatn=ios) meal ``` So far I’m at 18 lines EDIT: 15 lines ```fortran program aoc_2022_01 use iso_fortran_env integer, allocatable :: eat(:) open(newunit=iunit,file='input.txt',form='formatted',iostat=ios) allocate(eat(1),source=0) do while (.not.is_iostat_end(ios)) read(iunit,'(i10)',blank='ZERO',iostat=ios) meal if (meal==0) then eat = [eat,meal] else eat(size(eat)) = eat(size(eat))+meal end if end do print "(*(a,:,i0))", 'elf ',maxloc(eat),' of ',size(eat),' ate ',maxval(eat),' calories' end program ``` Maybe I should use FORTRAN77, that would save further bloat… ---
**Author:** ![nshaffer](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/nshaffer/32/161_2.png) [@nshaffer](https://fortran-lang.discourse.group/u/nshaffer)\ **Post date:** [December 2, 2022, 5:35am UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816/14 "2022-12-02T05:35:53Z")
For Day 2, I got really nice mileage out of the INDEX intrinsic, to look up values in a 3x3 payoff matrix. ---
**Author:** ![Carltoffel](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/carltoffel/32/1680_2.png) [@Carltoffel](https://fortran-lang.discourse.group/u/Carltoffel)\ **Post date:** [December 2, 2022, 6:20am UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816/15 "2022-12-02T06:20:02Z")
> [@awvwgk](#): > > I am probably going to do most of them in awk again, much fun. Understandable, you have basically `awk` in your name: `AWvwgK` 😃 ---
**Author:** ![RonShepard](https://avatars.discourse-cdn.com/v4/letter/r/a3d4f5/32.png) [@RonShepard](https://fortran-lang.discourse.group/u/RonShepard)\ **Post date:** [December 2, 2022, 7:01am UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816/16 "2022-12-02T07:01:07Z")
If you want to shorten the code, then remove the FileName parameter and place the name literal directly in the open statement. Remove the declarations to `unit, ios, meal` since they are implicit integer anyway. You can remove the close() statement since the file will be closed anyway at the program end. Also, if you just want to reduce the number of lines, then put the entire program on one line with the statements separated with semicolons. ---
**Author:** ![Carltoffel](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/carltoffel/32/1680_2.png) [@Carltoffel](https://fortran-lang.discourse.group/u/Carltoffel)\ **Post date:** [December 2, 2022, 2:56pm UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816/17 "2022-12-02T14:56:47Z")
I have some ideas to save more lines: - don’t use `program`, `end` es enough - you don’t need an `else` and `if` can then be one line - `iso_fortran_env` isn’t used ---
**Author:** ![FedericoPerini](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/federicoperini/32/1750_2.png) [@FedericoPerini](https://fortran-lang.discourse.group/u/FedericoPerini)\ **Post date:** [December 2, 2022, 5:30pm UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816/18 "2022-12-02T17:30:44Z")
> [@Carltoffel](#): > > don’t use `program` nice trick I didn’t know about! I was also thinking of replacing if/then/else with an arithmetic if. EDIT: the whole program could be refactored as ```fortran integer, allocatable :: eat(:) open(newunit=iunit,file='input.txt',form='formatted') allocate(eat(1),source=0) 1 read(iunit,'(i10)',blank='ZERO',err=5,end=5) meal 2 if (meal) 3,3,4 3 eat = [eat,meal]; goto 1 4 eat(size(eat)) = eat(size(eat))+meal; goto 1 5 print "(*(a,:,i0))", 'elf ',maxloc(eat),' of ',size(eat),' ate ',maxval(eat),' calories' end program ``` now down to 9 lines! ---
**Author:** ![sblionel](https://yyz2.discourse-cdn.com/free1/user_avatar/fortran-lang.discourse.group/sblionel/32/853_2.png) [@sblionel](https://fortran-lang.discourse.group/u/sblionel)\ **Post date:** [December 2, 2022, 9:32pm UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816/19 "2022-12-02T21:32:39Z")
For day 2 (second part) I used FINDLOC instead of INDEX. I thought what I ended up with was rather elegant. ---
**Author:** ![FortranFan](https://avatars.discourse-cdn.com/v4/letter/f/96bed5/32.png) [@FortranFan](https://fortran-lang.discourse.group/u/FortranFan)\ **Post date:** [December 3, 2022, 12:57am UTC](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816/20 "2022-12-03T00:57:14Z")
> [@FedericoPerini](#): > > now down to 9 lines! @FedericoPerini , did you test your code? Was not the task the one listed [**here**](https://adventofcode.com/2022/day/1) i.e., on the penultimate line in the link? If you care to strive for some code readability, a level of correctness, and the fewest characters in code as opposed to fewest lines which makes little sense, you might consider the following: > **Click to reveal code** > > ```fortran > open(7,file='input.txt',form='formatted') ; n = 1 ; m = 0 ; k = 0 ; mtk1 = -1; mtk2 = -1; mtk3 = -1; nk = 0 > do ; read(7,fmt='(bn,i9)',iostat=i) k ; if (i > 0) then ; print *, i ; stop ; end if ; if ( i < 0 ) exit > if (k == 0) then ; if (mtk1 < nk) then ; m = n ; mtk1 = nk ; else if (mtk2 < nk) then ; mtk2 = nk > else if (mtk3 < nk) then ; mtk3 = nk ; end if > n = n + 1; nk = 0 ; cycle ; end if > nk = nk + k ; end do > if (m > 0) then ; print "(*(g0))", " elf #", m, " is carrying ", mtk1, " calories." > print "(*(g0))", " Top 3 elves are carrying ", mtk1+mtk2+mtk3, " calories." ; end if > end > > ``` > > ```auto > C:\temp>gfortran p.f90 -o p.exe > > C:\temp>p.exe > elf #69 is carrying 71023 calories. > Top 3 elves are carrying 203942 calories. > > ``` [Next page](https://fortran-lang.discourse.group/t/advent-of-code-2022/4816.md?page=2)