.git-crypt/.gitattributes

@@ -0,0 +1,4 @@
+# Do not edit this file.  To specify the files to encrypt, create your own
+# .gitattributes file in the directory where your files are.
+* !filter !diff
+*.gpg binary

.gitattributes

@@ -0,0 +1 @@
+session.key filter=git-crypt diff=git-crypt

.gitignore

@@ -1,2 +1,7 @@
+# binaries
+**/first
+**/second
+**/both
+
 # input files
-input.txt
+**/input.txt

2022/01/both.nim

@@ -0,0 +1,38 @@
+import
+  std/strformat,
+  std/strutils
+
+when defined(second):
+  import
+    std/algorithm,
+    std/math
+
+import
+  ../../adventofcode
+
+let input = adventofcode.getInput()
+
+when not defined(second):
+  var mostCalories = 0
+else:
+  var elveCalories: seq[int]
+
+let inventories = input.split("\L\L")
+for inventory in inventories:
+  var calories = 0
+  let items = inventory.split("\L")
+  for item in items:
+    calories += item.parseInt()
+
+  when not defined(second):
+    mostCalories = max(mostCalories, calories)
+  else:
+    elveCalories.add calories
+
+when not defined(second):
+  echo fmt"Answer: {mostCalories}"
+else:
+  elveCalories.sort(order=Descending)
+  
+  let totalCalories = sum elveCalories[0 ..< 3]
+  echo fmt"Answer: {totalCalories}"

2022/02/first.nim

@@ -0,0 +1,43 @@
+import
+  std/strformat,
+  std/strutils,
+  std/tables
+
+import
+  ../../adventofcode
+
+let input = adventofcode.getInput()
+
+var score = 0
+
+type
+  Choices = enum
+    rock, paper, scissors
+
+let choices = toTable({
+  'A': rock,
+  'B': paper,
+  'C': scissors,
+  'X': rock,
+  'Y': paper,
+  'Z': scissors,
+})
+
+for line in input.splitLines:
+  let opponentChoice = choices[line[0]]
+  let ourChoice = choices[line[2]]
+
+  # The choice we make is added to the score
+  score += 1 + ord ourChoice
+
+  let outcome = ord(ourChoice) - ord(opponentChoice)
+  case outcome
+  of -2: score += 6
+  of -1: score += 0
+  of 0: score += 3
+  of 1: score += 6
+  of 2: score += 0
+  else:
+    raise newException(ValueError, fmt"Outcome: {outcome}")
+
+echo fmt"Answer: {score}"

2022/02/second.nim

@@ -0,0 +1,60 @@
+import
+  std/strformat,
+  std/strutils,
+  std/tables
+
+import
+  ../../adventofcode
+
+let input = adventofcode.getInput()
+
+var score = 0
+
+type
+  Choice = enum
+    cRock = 'A',
+    cPaper = 'B',
+    cScissors = 'C'
+  RequiredOutcome = enum
+    roDefeat = 'X',
+    roDraw = 'Y',
+    roVictory = 'Z'
+
+let choiceScores = toTable({
+  cRock: 1,
+  cPaper: 2,
+  cScissors: 3,
+})
+
+for line in input.splitLines:
+  let opponentChoice = Choice line[0]
+  let requiredOutcome = RequiredOutcome line[2]
+  var ourChoice: Choice
+  
+  case requiredOutcome
+  of roDefeat:
+    score += 0
+    case opponentChoice
+    of cRock:
+      ourChoice = cScissors
+    of cPaper:
+      ourChoice = cRock
+    of cScissors:
+      ourChoice = cPaper
+  of roDraw:
+    score += 3
+    ourChoice = opponentChoice
+  of roVictory:
+    score += 6
+    case opponentChoice
+    of cRock:
+      ourChoice = cPaper
+    of cPaper:
+      ourChoice = cScissors
+    of cScissors:
+      ourChoice = cRock
+
+  # The choice we make is added to the score
+  score += choiceScores[ourChoice]
+
+echo fmt"Answer: {score}"

2022/03/both.nim

@@ -0,0 +1,50 @@
+import
+  std/sequtils,
+  std/strformat,
+  std/strutils
+
+import
+  ../../adventofcode
+
+let input = adventofcode.getInput()
+
+var answer = 0
+
+let itemTypePriorities = block:
+  toSeq "-abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+
+when not defined(second):
+  for rucksack in input.splitLines:
+    let items = toSeq rucksack
+    let cmp1 = items[0 ..< items.len() div 2]
+    let cmp2 = items[items.len() div 2 .. ^1]
+
+    for item in cmp1:
+      if item in cmp2:
+        answer += itemTypePriorities.find item
+        break
+else:
+  let inputLines = input.splitLines()
+
+  iterator groups*(): tuple[
+    itemList1: seq[char],
+    itemList2: seq[char],
+    itemList3: seq[char]
+  ] =
+    var i = 0
+    while i < inputLines.len():
+      yield (
+        toSeq inputLines[i],
+        toSeq inputLines[i+1],
+        toSeq inputLines[i+2]
+      )
+      i += 3
+
+  for rucksack1, rucksack2, rucksack3 in groups():
+    for item in rucksack1:
+      if item notin rucksack2: continue
+      if item notin rucksack3: continue
+      answer += itemTypePriorities.find item
+      break
+
+echo fmt"Answer: {answer}"

2022/04/both.nim

@@ -0,0 +1,41 @@
+import
+  std/strformat,
+  std/strutils
+
+import
+  ../../adventofcode
+
+let input = adventofcode.getInput()
+
+var score = 0
+
+for pair in input.splitLines:
+  let sepIdx = pair.find(',')
+  assert sepIdx != -1
+
+  let range1Str = pair[0 ..< sepIdx]
+  let range2Str = pair[sepIdx + 1 .. ^1]
+  var range1: set[0 .. 65535]
+  var range2: set[0 .. 65535]
+
+  for i in 0 .. 1:
+    let rangeStr = block:
+      if i == 0: range1Str
+      else: range2Str
+    let rangeStrSepIdx = rangeStr.find('-')
+    assert rangeStrSepIdx != -1
+    let rangeStart = parseInt rangeStr[0 ..< rangeStrSepIdx]
+    let rangeEnd = parseInt rangeStr[rangeStrSepIdx + 1 .. ^1]
+    if i == 0: range1 = {rangeStart .. rangeEnd}
+    else: range2 = {rangeStart .. rangeEnd}
+
+  var total = range1 + range2
+  when not defined(second):
+    if range1.len == total.len or range2.len == total.len:
+      score += 1
+  else:
+    if total.len != (range1.len + range2.len):
+      score += 1
+
+echo fmt"Answer: {score}"
+

2022/05/both.nim

@@ -0,0 +1,84 @@
+import
+  std/algorithm,
+  std/sequtils,
+  std/strformat,
+  std/strutils
+
+import
+  ../../adventofcode
+
+let input = adventofcode.getInput()
+let lines = input.splitLines()
+
+var stacks = newSeq[seq[char]]()
+
+let sepIdx = lines.find("")
+assert sepIdx != -1
+let drawInstructions = lines[0 ..< sepIdx]
+let moveInstructions = lines[sepIdx + 1 .. ^1]
+
+when not defined(release):
+  proc echoRepr(stacks: seq[seq[char]]) =
+    let m = max stacks.mapIt(high it)
+    for i in countdown(m, 0):
+      echo join(stacks.map(proc(it: seq[char]): string =
+        if it.high < i: return "   "
+        return fmt"[{it[i]}]"
+      ), sep=" ")
+      
+    echo " " & join(toSeq {1 .. stacks.high() + 1}, "   ") & " "
+    
+for line in reversed drawInstructions:
+  if line.startsWith(" 1 "):
+    for n in line.splitWhitespace().mapIt(parseInt it):
+      assert n - 1 == len stacks
+      stacks.add(@[])
+  else:
+    var containers = newSeq[string]()
+    for i in countup(0, line.len - 2, 4):
+      containers.add line[i ..< i + 3]
+    for i in 0 ..< containers.len():
+      let cnt = containers[i]
+      if cnt[1] == ' ': continue
+      stacks[i].add cnt[1]
+
+when not defined(release) and defined(stepByStep):
+  echoRepr stacks
+  echo ""
+
+for line in moveInstructions.mapIt(it.splitWhitespace()):
+  when not defined(release) and defined(stepByStep):
+    echo line
+    echo ""
+
+  let howMany = parseInt line[1]
+  var srcStack = parseInt line[3]
+  srcStack.dec()
+  var destStack = parseInt line[5]
+  destStack.dec()
+
+  assert howMany <= len stacks[srcStack]
+
+  let sliceStart = stacks[srcStack].len() - howMany
+  let sliceEnd = stacks[srcStack].len() - 1
+  let movedItems = block:
+    when not defined(second):
+      reversed stacks[srcStack][sliceStart .. sliceEnd]
+    else:
+      stacks[srcStack][sliceStart .. sliceEnd]
+  stacks[srcStack].delete(sliceStart .. sliceEnd)
+  stacks[destStack] &= movedItems
+
+  when not defined(release) and defined(stepByStep):
+    echoRepr stacks
+    echo ""
+    echo "Press ENTER to continue."
+    discard stdin.readChar()
+    echo ""
+
+when not defined(release):
+  echoRepr stacks
+  echo ""
+
+let answer = join(stacks.mapIt it[high it])
+echo fmt "Answer: {answer}"

2022/06/both.nim

@@ -0,0 +1,35 @@
+import
+  std/strformat
+
+import
+  ../../adventofcode
+
+let input = adventofcode.getInput()
+
+const markerLen = block:
+  when not defined(second):
+    4
+  else:
+    14
+var queue = newSeq[char](markerLen)
+var answer: int
+
+block process:
+  for i in 0 ..< len input:
+    let dup = input[i] in queue
+    discard queue.pop()
+    queue.insert(input[i], 0)
+    assert markerLen == len queue
+
+    if not dup and i >= markerLen:
+      block check:
+        for j in 0 ..< len queue:
+          for k in 0 ..< len queue:
+            if j == k: continue
+            if queue[k] == queue[j]:
+              break check
+
+        answer = i + 1
+        break process
+
+echo fmt"Answer: {answer}"

adventofcode.nim

@@ -1,26 +1,63 @@
+#[
+  This file works by doing a lot of assumptions
+  about the project folder structure.
+
+  For instance, it assumes the executable
+  directory to be something in a "YYYY/DD"
+  format.
+
+  It also assumes the session key to be
+  available at the project root.
+  (in other words "../../session.key")
+]#
+
 import
   std/httpclient,
   std/os,
   std/strformat,
   std/strutils
+
+when isMainModule:
+  stderr.writeLine "adventofcode> This can not be ran directly."
+  quit 1
+
+let sessionKeyPath = os.getAppDir() / ".." / ".." / "session.key"
+if not fileExists sessionKeyPath:
+  stderr.writeLine "adventofcode> secret.key could not be found."
+let sessionKey = readFile sessionKeyPath
+if sessionKey[0 ..< 10] == "\x00GITCRYPT\x00":
+  stderr.writeLine "adventofcode> secret.key is encrypted."
+  quit 1
   
 proc getInput*(year, day: int): string =
-  try:
-    let input = readFile(getCurrentDir() / "input.txt")
+  ## Automatically downloads the input from
+  ## AdventOfCode, unless there is a local copy
+  ## of the input as 'input.txt' in the app dir.
+  let inputPath = os.getAppDir() / "input.txt"
+  if fileExists inputPath:
+    echo "adventofcode> Proceeding with current input.txt file."
+    let input = readFile inputPath
     
     return input.strip(chars = {'\n'})
-  except IOError:
+  else:
     echo "adventofcode> Missing input.txt. Downloading..."
-    let session = os.getEnv("SESSION")
-    if session == "":
-      echo "adventofcode> Unable to download without the SESSION environment variable."
-      quit 1
 
     let client = newHttpClient()
-    client.headers = newHttpHeaders({ "Cookie": fmt"session={session}" })
+    client.headers = newHttpHeaders({ "Cookie": fmt"session={sessionKey}" })
 
     let input = client.getContent fmt"https://adventofcode.com/{year}/day/{day}/input"
     
-    writeFile(getCurrentDir() / "input.txt", input)
+    writeFile(inputPath, input)
     
-    return input.strip(chars = {'\n'})
+    return input.strip(chars = {'\n'})
+
+proc getInput*(): string =
+  ## Tries to determine year and date of
+  ## day by looking at the app dir path.
+  let day = block:
+    let p = os.getAppDir().splitPath()
+    p.tail.parseInt()
+  let year = block:
+    let p = os.getAppDir().parentDir().splitPath()
+    p.tail.parseInt()
+  result = getInput(year, day)