Day 23, Part 1

README.md

@@ -5,6 +5,6 @@ I started learning Haskell very recently, and I just learned this year that Adve
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 |01 |★ ★  |06 |★ ★  |11 |★ ★  |16 |★    |21 |     |
 |02 |★ ★  |07 |★ ★  |12 |★    |17 |★ ★  |22 |★    |
-|03 |★ ★  |08 |★ ★  |13 |★ ★  |18 |★ ★  |23 |     |
+|03 |★ ★  |08 |★ ★  |13 |★ ★  |18 |★ ★  |23 |★    |
 |04 |★ ★  |09 |★ ★  |14 |★ ★  |19 |★    |24 |     |
 |05 |★ ★  |10 |★ ★  |15 |★    |20 |     |25 |     |

adventofcode2024.cabal

@@ -58,4 +58,5 @@ executable adventofcode2024
     Day18
     Day19
     Day22
+    Day23
     Graph

src/Day16.hs

@@ -50,5 +50,4 @@ day16_1 = do
   (mazeMap, nRow, nCol) <- parseInput
   let (mazeGraph, start, end) = getMazeGraph mazeMap nRow nCol
       shortestPaths = [findShortestPath mazeGraph start e | e <- end]
-  --  putStrLn $ "Day 16, Puzzle 1 solution: " ++ show (findShortestPath mazeGraph start end)
   putStrLn $ "Day 16, Puzzle 1 solution: " ++ show (minimum shortestPaths)

src/Day23.hs

@@ -0,0 +1,40 @@
+module Day23 (day23_1) where
+
+import Control.Monad
+import Data.Containers.ListUtils (nubOrd)
+import Data.List (nub, sort)
+import Data.List.Split (splitOn)
+
+startsWithT :: String -> Bool
+startsWithT [] = False
+startsWithT (x : _)
+  | x == 't' = True
+  | otherwise = False
+
+getConns3 :: [[String]] -> [[String]]
+getConns3 connections = do
+  conn1 <- connections
+  conn2 <- connections
+
+  guard $
+    conn1 /= conn2
+      && length (nub (conn1 ++ conn2)) == 3
+      && any startsWithT (conn1 ++ conn2)
+
+  conn3 <- connections
+
+  guard $
+    conn1 /= conn3
+      && conn2 /= conn3
+      && length (nub (conn1 ++ conn2 ++ conn3)) == 3
+      && any startsWithT (conn1 ++ conn2 ++ conn3)
+
+  return . nub $ conn1 ++ conn2 ++ conn3
+
+day23_1 :: IO ()
+day23_1 = do
+  contents <- lines <$> readFile "input/day23.txt"
+  let connections = map (splitOn "-") contents
+  putStrLn $
+    "Day 23, Puzzle 1 solution: "
+      ++ show (length . nubOrd . map sort $ getConns3 connections)

src/Main.hs

@@ -20,6 +20,7 @@ import Day17 (day17_1, day17_2)
 import Day18 (day18_1, day18_2)
 import Day19 (day19_1)
 import Day22 (day22_1)
+import Day23 (day23_1)
 import System.Environment (getArgs)
 
 main :: IO ()
@@ -106,6 +107,7 @@ main = do
       day18_2
     "19" : "1" : _ -> day19_1
     "22" : "1" : _ -> day22_1
+    "23" : "1" : _ -> day23_1
     "all" : _ -> do
       day01_1
       day01_2
@@ -142,4 +144,5 @@ main = do
       day18_2
       day19_1
       day22_1
+      day23_1
     _ -> error "Not implemented"