.gitignore

@@ -1,6 +1,7 @@
 # binaries
 **/first
 **/second
+**/both
 
 # input files
 **/input.txt

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}"