Day 15: Lens Library

Megathread guidelines

  • Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
  • Code block support is not fully rolled out yet but likely will be in the middle of the event. Try to share solutions as both code blocks and using something such as https://topaz.github.io/paste/ , pastebin, or github (code blocks to future proof it for when 0.19 comes out and since code blocks currently function in some apps and some instances as well if they are running a 0.19 beta)

FAQ

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  • janAkaliEnglish
    3•7 months ago

    Nim

    My whole solution can be expressed in just two words: Ordered HashTable

    Total runtime: 0.068 line-seconds (40 LOC * 1.7 ms)
    Puzzle rating: exceptionally confusing description 4/10
    Code: cleaned up solution with types
    Snippet:

    proc getHash(s: string): int =
  for c in s:
    result = ((result + c.ord) * 17) mod 256

proc solve(lines: seq[string]): AOCSolution[int] =
  var boxes: array[256, OrderedTable[string, int]]
  for line in lines:
    block p1:
      result.part1 += line.getHash()

    block p2:
      if line.endsWith('-'):
        var name = line.strip(leading=false, chars={'-'})
        boxes[getHash(name)].del(name)
      else:
        let (name, _, value) = line.partition("=")
        boxes[getHash(name)][name] = value[0].ord - '0'.ord

  for bi, box in boxes:
    if box.len < 1: continue
    for vi, val in enumerate(box.values):
      result.part2 += (bi+1) * (vi+1) * val