From 661ae7a8b4e0601aae8bfbf1708b894b4ade2b4d Mon Sep 17 00:00:00 2001
From: Orfeas Chatzipanagiotis <csd4366@csd.uoc.gr>
Date: Fri, 9 Dec 2022 04:40:44 +0200
Subject: Day 5

---
 day5/solution.nim | 87 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 87 insertions(+)
 create mode 100644 day5/solution.nim

(limited to 'day5/solution.nim')

diff --git a/day5/solution.nim b/day5/solution.nim
new file mode 100644
index 0000000..2bf41aa
--- /dev/null
+++ b/day5/solution.nim
@@ -0,0 +1,87 @@
+import std/strutils
+import std/sequtils
+import std/enumerate
+import std/algorithm
+import std/re
+
+type
+  Move = tuple 
+    Amount: int
+    From: int
+    To: int
+
+  Stack = seq[char]
+
+  Input = tuple
+    Stacks: seq[Stack]
+    Moves: seq[Move]
+
+proc parseContent(content: string): Input =
+  # Parse stacks
+  let tokens = content.split("\n\n")
+  var strStacks = map(
+      # All lines containing characters of the stacks 
+      # Exclude last line since it contain's each stack's id
+      tokens[0].splitLines()[0 .. ^2],
+      proc(line: string): string =
+        var retval = ""
+        # keep only the relevant characters (spaces/letters)
+        for i in countup(1, line.len(), 4):
+          retval.add(line[i])
+        retval
+      )
+
+  var Stacks = newSeq[Stack](10)
+
+  for layer in strStacks:
+    for i, c in enumerate(layer):
+      if c != ' ':
+        Stacks[i+1].add(c)
+
+  var strMoves = map(
+      # All moves described in the input
+      tokens[1].strip().splitLines(),
+      proc(line: string): seq[int] = 
+        # Remove words and split on spaces
+        let tokens = line.replace(re"[a-z]+ ").split(" ")
+        # Parse them as integers
+        map(tokens, proc (num: string): int = num.parseInt())
+      )
+
+  var Moves: seq[Move]
+  for move in strMoves:
+    Moves.add((move[0], move[1], move[2]))
+
+  return (Stacks, Moves)
+
+proc makeMove(stacks: var seq[Stack], move: Move, inPlace = false): void =
+  # copy top of the stack
+  var yoink = stacks[move.From][0 ..< move.Amount]
+  # moving in place preserves the order of the moved crates (part2)
+  if not inPlace:
+    yoink.reverse()
+  # remove it from origin
+  stacks[move.From].delete(0 ..< move.Amount)
+  # concat it in front of destination
+  stacks[move.To] = concat(yoink, stacks[move.To])
+
+proc getAnswer(stacks: seq[Stack]): string =
+  var answer = ""
+  for stack in stacks:
+    if stack.len() > 0:
+      answer.add(stack[0])
+  answer
+
+let content = readFile("./input.txt")
+var input = parseContent(content)
+
+let moves = input.Moves
+var stacksPart1 = input.Stacks
+var stacksPart2 = input.Stacks
+
+for move in moves:
+  makeMove(stacksPart1, move)
+  makeMove(stacksPart2, move, true)
+
+echo getAnswer(stacksPart1)
+echo getAnswer(stacksPart2)
-- 
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