AoC 2023 day 5

advent.nim

# nim compile --run day#/advent.nim demo 1
# nim compile --run day#/advent.nim demo 2
# nim compile --run day#/advent.nim one
# nim compile --run day#/advent.nim two
import os
import strutils
import sequtils
import sets

proc challenge(file: string, challenge: int): void =
  let input = multiReplace(readFile(file), [("\r", "")])

  var inputAndMappings = input.split("\n\n")
  var curNums = inputAndMappings[0][inputAndMappings[0].find(":")+2 .. high(
      inputAndMappings[0])].split(" ").map(proc(
      n: string): int64 = n.parseInt.int64)
  # get initial seeds as range
  var seeds: seq[array[2, int64]]
  if challenge == 1:
    for num in curNums:
      seeds.add([num, num])
  else:
    for i in countup(0, (curNums.len/2).int-1):
      seeds.add([curNums[i*2], curNums[i*2]+curNums[i*2+1]-1])
  echo seeds

  for i in 1 .. high(inputAndMappings):
    var instruct = inputAndMappings[i].split('\n')
    var name = instruct[0]
    instruct.delete(0, 0)
    # transformation line as numbers
    var tran = instruct.map(proc(l: string): seq[int] = l.split(' ').map(proc(
        n: string): int = n.parseInt))
    echo name
    var mapped: seq[array[2, int64]]
    for t in tran:
      var dest = t[0].int64
      var source = t[1].int64
      var step = t[2].int64
      var diff = dest-source
      var i = 0
      while i < seeds.len:
        if seeds[i][1] < source or seeds[i][0] > source+step-1:
          i+=1
          continue
        # first half of range matches
        if seeds[i][0] < source and seeds[i][1] < source + step - 1 and seeds[
            i][1] >= source:
          #echo "left", seeds[i]
          mapped.add([dest, seeds[i][1]+diff])
          seeds[i] = [seeds[i][0], source-1]
        # second half of range matches
        if seeds[i][1] > source + step - 1 and seeds[i][0] > source and seeds[
            i][0] <= source + step - 1:
          #echo "right", seeds[i]
          mapped.add([seeds[i][0]+diff, dest+step-1])
          seeds[i] = [source+step, seeds[i][1]]
        # whole range matches/smaller
        if seeds[i][0] >= source and seeds[i][1] <= source + step - 1:
          #echo "min", seeds[i]
          mapped.add([seeds[i][0]+diff, seeds[i][1]+diff])
          seeds.delete(i)
          i-=1
        #echo "seeds:", seeds, " mapped:", mapped
        i+=1
    if seeds.len > 0:
      mapped &= seeds
    seeds = mapped
    #echo seeds
  var min = seeds[0][0]
  for seed in seeds:
    if seed[0] < min:
      min = seed[0]
  echo min
  # pt 2: 63092906 too high

if paramStr(1) == "demo":
  challenge("./demo.txt", parseInt(paramStr(2)))
elif paramStr(1) == "one":
  challenge("./input.txt", 1)
else:
  challenge("./input.txt", 2)