diff --git a/inputs/2023/18.txt b/inputs/2023/18.txt
new file mode 100644
index 0000000..d7ef926
--- /dev/null
+++ b/inputs/2023/18.txt
@@ -0,0 +1,606 @@
+R 3 (#6289d0)
+U 2 (#6a5a63)
+R 3 (#49a250)
+U 9 (#290bb3)
+R 6 (#8ec710)
+D 8 (#838413)
+R 4 (#387a10)
+D 3 (#32f593)
+R 4 (#3a8d10)
+U 7 (#a252a3)
+R 3 (#500100)
+U 5 (#03c113)
+R 4 (#28fc32)
+U 6 (#6da763)
+R 4 (#033882)
+D 8 (#0aa563)
+R 2 (#3c2ae2)
+D 3 (#79df03)
+R 5 (#7a1652)
+D 8 (#79df01)
+R 6 (#27e8a2)
+U 7 (#65f7a3)
+R 3 (#911302)
+U 5 (#58f723)
+R 8 (#6289d2)
+U 4 (#93bed3)
+L 11 (#5d5922)
+U 3 (#5552d3)
+R 9 (#7d6f62)
+U 3 (#17eec3)
+L 8 (#a06f82)
+U 3 (#068273)
+L 2 (#1aadb0)
+U 4 (#7f20e3)
+L 7 (#6895c0)
+U 3 (#141553)
+L 5 (#2ae520)
+U 5 (#141551)
+R 5 (#87e540)
+U 6 (#1d5593)
+L 6 (#2f8912)
+U 2 (#43b2e3)
+L 3 (#79f0f2)
+D 8 (#43b2e1)
+L 3 (#27a892)
+D 3 (#274813)
+L 3 (#64eb42)
+D 3 (#77cf23)
+L 3 (#9ac052)
+D 3 (#5d6873)
+L 5 (#1e96b2)
+D 6 (#1b83b3)
+L 5 (#981b40)
+U 4 (#13e0e1)
+L 11 (#367430)
+D 4 (#8b4bc3)
+L 5 (#4c6d40)
+U 9 (#8b4bc1)
+R 2 (#3eefd0)
+U 3 (#13e0e3)
+R 6 (#583170)
+U 4 (#a413d3)
+R 6 (#356a00)
+U 6 (#a413d1)
+R 8 (#4d0710)
+U 4 (#151eb3)
+R 3 (#838e10)
+U 6 (#34b913)
+R 4 (#2ef720)
+U 5 (#4a8523)
+R 7 (#34ca90)
+D 5 (#077023)
+R 4 (#747f00)
+U 3 (#077021)
+R 8 (#1a3150)
+U 6 (#4096d3)
+R 10 (#44a9e2)
+U 6 (#2a7c03)
+L 10 (#7ed102)
+U 4 (#46ea63)
+R 3 (#2acd60)
+U 3 (#9799c3)
+L 4 (#050c60)
+U 6 (#44c4b3)
+L 3 (#01e230)
+U 5 (#50ee91)
+L 3 (#3bfdd0)
+U 3 (#1c9603)
+L 7 (#2aa6d2)
+U 4 (#71db13)
+L 8 (#2aa6d0)
+D 7 (#31c943)
+L 9 (#4ccc60)
+D 4 (#2ca231)
+R 9 (#1402e0)
+D 5 (#939821)
+L 4 (#668400)
+D 2 (#4d4fa1)
+L 8 (#210230)
+U 8 (#3e2041)
+L 4 (#085470)
+U 3 (#404733)
+L 6 (#00c2b0)
+U 4 (#5be0c3)
+L 4 (#2b5df0)
+U 9 (#5fde53)
+R 4 (#83a0d0)
+U 9 (#795c63)
+R 3 (#814530)
+U 4 (#7f37e3)
+R 5 (#266850)
+D 5 (#659c43)
+R 7 (#266852)
+U 5 (#6b5593)
+R 9 (#a9e230)
+D 7 (#4d39a1)
+R 9 (#1a48b0)
+D 6 (#4f83f1)
+R 4 (#26ebe0)
+D 5 (#742f43)
+R 5 (#5443a0)
+U 5 (#742f41)
+R 6 (#3e64a0)
+U 2 (#1f6681)
+R 9 (#b99422)
+U 5 (#520eb1)
+L 6 (#27d510)
+U 6 (#0bba61)
+L 4 (#3ad3c0)
+U 5 (#92bca1)
+L 7 (#3ad3c2)
+U 5 (#200a11)
+L 6 (#4493c0)
+U 3 (#25dc51)
+L 5 (#6a5560)
+U 6 (#772071)
+L 4 (#264bf0)
+D 3 (#2719e1)
+L 5 (#90a152)
+D 6 (#1cbb11)
+L 4 (#4493c2)
+D 3 (#452e71)
+L 4 (#27d512)
+D 2 (#5dd971)
+L 8 (#1c4610)
+U 6 (#096103)
+R 5 (#8438f0)
+U 6 (#7351f3)
+R 4 (#057e10)
+U 6 (#0164e3)
+R 6 (#4f7390)
+U 3 (#2721c3)
+R 4 (#60ab50)
+U 6 (#4fb023)
+R 10 (#35dad0)
+U 2 (#4fb021)
+R 5 (#331620)
+U 7 (#157f73)
+R 9 (#618be0)
+U 2 (#36ac23)
+R 4 (#4c6400)
+U 9 (#36ac21)
+R 3 (#43b840)
+U 3 (#7159c3)
+L 7 (#44d610)
+U 5 (#155933)
+R 7 (#0991f2)
+U 5 (#577cc3)
+R 4 (#5c9bf2)
+U 3 (#05f3e3)
+R 7 (#4861f2)
+U 4 (#6c7323)
+R 7 (#6268b2)
+D 6 (#1cb853)
+R 2 (#23b182)
+D 3 (#34c9c3)
+L 7 (#01d432)
+D 8 (#0f5423)
+L 2 (#84c4f0)
+D 3 (#3f1e13)
+R 9 (#0cc5a0)
+D 5 (#57adb3)
+R 9 (#016840)
+D 4 (#677883)
+R 7 (#4b8150)
+D 7 (#584523)
+R 8 (#5bfe40)
+D 3 (#11d461)
+L 8 (#129982)
+D 7 (#51ede1)
+R 3 (#129980)
+D 9 (#5bfb61)
+R 3 (#20ef20)
+D 3 (#4d9bc3)
+R 6 (#3c2e70)
+D 3 (#43eb41)
+L 6 (#64a590)
+D 2 (#19ee91)
+L 4 (#17c8d0)
+D 7 (#975651)
+L 6 (#4d78f0)
+D 2 (#5af991)
+L 3 (#15f1b0)
+D 4 (#581221)
+R 6 (#254700)
+D 6 (#26e793)
+R 4 (#1b6f00)
+D 4 (#681fc3)
+L 4 (#364020)
+D 8 (#511d31)
+L 6 (#548950)
+D 6 (#3dea21)
+R 6 (#04fc90)
+D 3 (#552a51)
+R 4 (#0e1762)
+D 10 (#2561b1)
+R 5 (#597e80)
+D 8 (#702b43)
+R 3 (#16eb00)
+D 4 (#702b41)
+R 4 (#5ad290)
+D 3 (#427b11)
+R 8 (#1e5d32)
+D 7 (#0416e1)
+R 4 (#2daa92)
+U 5 (#28bc11)
+R 3 (#4019e2)
+U 5 (#8e2311)
+R 8 (#052a72)
+U 3 (#528623)
+L 8 (#1ea522)
+U 5 (#0cbf83)
+R 6 (#1ea520)
+U 5 (#5bb063)
+R 6 (#39f002)
+U 6 (#64e7e1)
+R 8 (#2f0402)
+U 3 (#3d83d3)
+R 6 (#70b5f2)
+U 2 (#7f4ba3)
+R 6 (#090b72)
+U 5 (#366de1)
+R 4 (#4b84c2)
+U 5 (#6b7cb1)
+R 3 (#763d12)
+D 6 (#1ae4e1)
+R 6 (#0e3542)
+U 6 (#560411)
+R 5 (#83a042)
+U 3 (#3bc341)
+R 3 (#4b7352)
+U 8 (#577fc1)
+R 7 (#626e42)
+U 4 (#13f5c1)
+R 5 (#a04f62)
+U 6 (#13f5c3)
+R 6 (#096972)
+U 2 (#2d6be1)
+R 4 (#0767e0)
+U 7 (#5be161)
+R 2 (#7d3600)
+U 8 (#440821)
+R 3 (#0fc190)
+U 3 (#61c671)
+L 3 (#07b370)
+U 10 (#430571)
+L 4 (#6f6970)
+U 5 (#43a653)
+L 8 (#1a5260)
+U 3 (#43a651)
+R 8 (#7107e0)
+U 7 (#10b3d1)
+L 8 (#024af2)
+U 7 (#16ed01)
+L 4 (#b255c2)
+U 2 (#099513)
+L 8 (#13d682)
+U 4 (#099511)
+R 3 (#b0f4a2)
+U 4 (#16ed03)
+R 3 (#1d6ac2)
+U 4 (#3295c1)
+R 8 (#1aa6b2)
+U 4 (#125d83)
+R 7 (#1dfb02)
+D 4 (#1bf363)
+R 3 (#2656e2)
+D 8 (#7d7303)
+R 7 (#2656e0)
+D 8 (#211f43)
+R 3 (#4592c2)
+D 7 (#292ae3)
+R 7 (#816e92)
+U 7 (#3898b3)
+R 5 (#4f4e62)
+D 5 (#86c423)
+R 3 (#7e59f2)
+D 9 (#27b271)
+R 3 (#1a02b2)
+D 6 (#03ce41)
+L 3 (#363970)
+D 9 (#b91bb1)
+L 2 (#363972)
+D 3 (#16cfd1)
+R 5 (#37ea82)
+D 3 (#0a2cd1)
+L 7 (#92d872)
+D 7 (#4c1711)
+L 4 (#01cbd2)
+D 7 (#4bc171)
+R 5 (#8efa50)
+D 5 (#7b2d31)
+R 6 (#0e9850)
+D 5 (#74ef91)
+R 7 (#7a37e0)
+D 3 (#6154e1)
+R 3 (#7baf00)
+U 5 (#17a443)
+R 8 (#532e00)
+U 6 (#17a441)
+R 10 (#8e0410)
+U 4 (#6154e3)
+R 5 (#6fca00)
+U 8 (#4b1103)
+L 6 (#833220)
+U 5 (#1e3033)
+L 3 (#54ef30)
+U 8 (#1e3031)
+L 2 (#9e7660)
+U 4 (#4b1101)
+L 3 (#064ae0)
+D 9 (#2b6491)
+L 2 (#83b470)
+D 3 (#2b6493)
+L 3 (#5a3a10)
+D 5 (#6bbba1)
+L 4 (#29afc0)
+U 10 (#235101)
+R 4 (#4a0f40)
+U 12 (#617f71)
+R 2 (#62e590)
+U 5 (#4d3611)
+R 7 (#4077e2)
+U 3 (#4763f1)
+L 5 (#81d5b2)
+U 5 (#6e1fd1)
+L 5 (#1107a2)
+U 5 (#020fa1)
+L 5 (#22b5f2)
+U 3 (#1d3841)
+R 6 (#13dff2)
+U 6 (#9501a1)
+R 6 (#4176b2)
+D 6 (#24aeb1)
+R 3 (#1d44c2)
+U 3 (#a77e53)
+R 5 (#00ad12)
+D 4 (#3179e3)
+R 3 (#42c9e2)
+D 8 (#65dbb1)
+R 2 (#9b6442)
+D 7 (#5bbda1)
+R 4 (#706b80)
+U 12 (#6b1e41)
+R 4 (#2c2250)
+D 9 (#5ef081)
+R 7 (#4d2c80)
+D 6 (#7e52d3)
+R 5 (#4004a0)
+D 2 (#340173)
+R 4 (#638190)
+D 8 (#a0e873)
+R 7 (#58e510)
+D 4 (#3f5041)
+L 11 (#14be32)
+D 2 (#350111)
+L 3 (#14be30)
+D 3 (#5f9dd1)
+L 3 (#1a6850)
+D 4 (#7f4d91)
+R 7 (#067bf0)
+D 7 (#600cf1)
+R 2 (#5ff142)
+U 7 (#10c9f1)
+R 8 (#63a502)
+D 7 (#3e29c1)
+R 6 (#58c402)
+D 6 (#653be1)
+R 4 (#66ee92)
+D 8 (#62d4d3)
+L 3 (#7532f2)
+D 3 (#62d4d1)
+L 4 (#0c8252)
+D 7 (#438151)
+L 6 (#63ce50)
+D 4 (#53bee1)
+L 3 (#274190)
+D 5 (#540a93)
+L 8 (#843930)
+U 5 (#540a91)
+L 6 (#38f5f0)
+U 4 (#5d2bc1)
+L 3 (#35e8d0)
+D 4 (#571381)
+L 2 (#22aed2)
+D 4 (#51c4d1)
+L 4 (#22aed0)
+D 2 (#1a6ca1)
+L 8 (#141aa0)
+D 4 (#16f0c1)
+L 5 (#69f5a0)
+D 3 (#50b081)
+L 11 (#4722c2)
+D 3 (#4cae83)
+L 2 (#864f82)
+D 2 (#62b293)
+L 10 (#083dd2)
+U 5 (#9863e3)
+L 6 (#3bfff2)
+D 2 (#160693)
+L 3 (#9b2bf2)
+U 4 (#471371)
+L 8 (#181952)
+D 4 (#53e531)
+L 3 (#292882)
+D 5 (#190d41)
+R 7 (#68fbb2)
+D 4 (#190d43)
+R 3 (#87a972)
+U 4 (#53e533)
+R 7 (#081782)
+D 6 (#8adf41)
+R 8 (#532c40)
+D 4 (#92bed1)
+R 4 (#5019e0)
+U 9 (#92bed3)
+R 5 (#782dc0)
+D 9 (#68fdd1)
+R 4 (#1e8a90)
+D 3 (#22db01)
+R 7 (#4f5c22)
+D 7 (#5a9031)
+R 7 (#4dc440)
+D 8 (#1adad1)
+R 2 (#1c5ed0)
+D 4 (#296441)
+R 8 (#7e80c0)
+D 5 (#6ccdd1)
+L 5 (#5ea2a2)
+D 4 (#4f7151)
+L 9 (#654fc2)
+D 3 (#2d7751)
+L 6 (#654fc0)
+D 4 (#3d0d31)
+L 5 (#3fc180)
+D 4 (#687ed1)
+R 5 (#5c6c60)
+D 3 (#08e123)
+R 5 (#369da0)
+D 2 (#5b9343)
+R 8 (#4a19d2)
+D 5 (#2fa453)
+L 6 (#4a19d0)
+D 9 (#3124e3)
+L 2 (#369da2)
+U 9 (#126ea3)
+L 5 (#47d330)
+D 3 (#9a27c1)
+L 5 (#65efc0)
+D 6 (#3d8471)
+L 5 (#105740)
+U 11 (#458fb1)
+L 3 (#160aa0)
+U 3 (#1f5a11)
+L 6 (#2eec42)
+U 8 (#0936f1)
+L 2 (#a2bc52)
+U 12 (#0936f3)
+L 3 (#197e52)
+D 8 (#7cff41)
+L 4 (#0b1b52)
+D 6 (#38ab61)
+L 4 (#7a1082)
+D 5 (#4cc4e1)
+L 4 (#098560)
+D 5 (#4cefe1)
+R 7 (#098562)
+D 5 (#7e3c91)
+R 9 (#8210d2)
+D 3 (#1f5193)
+L 7 (#4ddcc2)
+D 6 (#331863)
+L 2 (#256540)
+U 6 (#478ea3)
+L 7 (#064712)
+D 3 (#61ebe3)
+L 6 (#064710)
+D 4 (#1ba8f3)
+L 4 (#256542)
+D 5 (#1abc53)
+L 4 (#4ddcc0)
+D 6 (#21e323)
+L 6 (#5a96e2)
+D 5 (#25a201)
+L 7 (#376d92)
+U 5 (#5cd0f1)
+L 3 (#110232)
+D 5 (#2c23e1)
+L 5 (#110230)
+D 4 (#3d4e61)
+R 4 (#4f94a2)
+D 5 (#4a2761)
+L 4 (#3bf242)
+D 6 (#1c13d1)
+L 3 (#788182)
+D 3 (#2e4db3)
+L 9 (#152c12)
+D 2 (#1d6453)
+L 3 (#251a52)
+D 3 (#9a5fc3)
+R 3 (#251a50)
+D 2 (#466ca3)
+R 9 (#6be6a2)
+D 5 (#25a203)
+L 7 (#318bb2)
+D 4 (#64d183)
+L 7 (#78f622)
+D 2 (#247fd3)
+L 8 (#78f620)
+D 3 (#75b6a3)
+L 2 (#57f542)
+D 5 (#277e03)
+L 4 (#773422)
+D 6 (#92c4a3)
+R 4 (#773420)
+D 7 (#3e42a3)
+L 7 (#800962)
+U 8 (#3be443)
+L 3 (#2d3bf2)
+U 13 (#2dc9b3)
+L 4 (#8dce92)
+D 9 (#69adf1)
+L 2 (#57b742)
+D 3 (#30bbf3)
+L 7 (#30f722)
+D 4 (#85ad43)
+L 9 (#8246b0)
+D 4 (#2181f3)
+L 7 (#796432)
+D 5 (#087563)
+L 8 (#3c7b92)
+D 4 (#8767e3)
+R 5 (#04a3c0)
+D 3 (#78ea63)
+R 8 (#04a3c2)
+D 3 (#4d8193)
+L 6 (#b5dfc0)
+D 2 (#0b8243)
+L 7 (#804ef0)
+D 4 (#471af1)
+L 6 (#14a462)
+D 8 (#64f7e1)
+L 7 (#1d1290)
+U 4 (#6788a1)
+L 4 (#1d1292)
+U 9 (#07ed81)
+L 2 (#14a460)
+U 3 (#25f601)
+L 6 (#1f4cb0)
+U 9 (#41ce71)
+L 3 (#a1dff0)
+U 8 (#137563)
+L 2 (#362e22)
+U 4 (#6eb543)
+L 6 (#6cccc2)
+U 5 (#3f5983)
+L 6 (#249900)
+U 4 (#3ef663)
+L 3 (#0a8c50)
+U 4 (#5decc3)
+L 10 (#0a8c52)
+U 2 (#452b53)
+L 9 (#249902)
+U 6 (#2a3c03)
+R 4 (#89f592)
+U 3 (#4ba633)
+R 8 (#2cc4e2)
+U 4 (#263133)
+L 9 (#913952)
+U 2 (#0fe923)
+L 3 (#059172)
+U 6 (#7c4313)
+L 10 (#73f222)
+U 4 (#5559d3)
+L 2 (#3cb6b2)
+U 8 (#2c70f1)
+L 5 (#5ffb22)
+D 9 (#0bf671)
+L 6 (#4d3512)
+U 9 (#ac5f51)
+L 4 (#27dc72)
+U 5 (#ac5f53)
+L 3 (#490342)
+U 8 (#0bf673)
+L 3 (#6fad62)
+U 8 (#6e2403)
diff --git a/solutions/solutions.cabal b/solutions/solutions.cabal
index 3501fe3..f768456 100644
--- a/solutions/solutions.cabal
+++ b/solutions/solutions.cabal
@@ -1070,3 +1070,7 @@ executable sln_2023_17
   import:              day
   main-is:             2023/17.hs
   build-depends:       array
+
+executable sln_2023_18
+  import:              day
+  main-is:             2023/18.hs
diff --git a/solutions/src/2023/18.hs b/solutions/src/2023/18.hs
new file mode 100644
index 0000000..63c9e07
--- /dev/null
+++ b/solutions/src/2023/18.hs
@@ -0,0 +1,94 @@
+{-# Language QuasiQuotes, DataKinds, TemplateHaskell, ImportQualifiedPost, GADTs #-}
+{-|
+Module      : Main
+Description : Day 18 solution
+Copyright   : (c) Eric Mertens, 2023
+License     : ISC
+Maintainer  : emertens@gmail.com
+
+<https://adventofcode.com/2023/day/18>
+
+>>> :{
+:main +
+"R 6 (#70c710)
+D 5 (#0dc571)
+L 2 (#5713f0)
+D 2 (#d2c081)
+R 2 (#59c680)
+D 2 (#411b91)
+L 5 (#8ceee2)
+U 2 (#caa173)
+L 1 (#1b58a2)
+U 2 (#caa171)
+R 2 (#7807d2)
+U 3 (#a77fa3)
+L 2 (#015232)
+U 2 (#7a21e3)
+"
+:}
+62
+952408144115
+
+-}
+module Main (main) where
+
+import Advent (format, stageTH)
+import Advent.Box (coverBoxes, intersectBox, size, subtractBox, Box(Pt, Dim), Box')
+import Advent.Coord (east, north, origin, scaleCoord, south, west, Coord(..))
+import Advent.Search (bfs)
+import Data.Maybe (isJust)
+import Numeric (readHex)
+
+data D = DD | DU | DL | DR
+
+stageTH
+
+-- |
+--
+-- >>> :main
+-- 41019
+-- 96116995735219
+main :: IO ()
+main =
+ do input <- [format|2023 18 (@D %d %(#%s%c%)%n)*|]
+    let part1 = [(n, d) | (d,n,_,_) <- input]
+    let part2 = [(fst (head (readHex str)), dir2 d) | (_,_,str,d) <- input]
+    print (solve part1)
+    print (solve part2)
+    
+solve :: [(Int, D)] -> Int
+solve input = sum (map size ditches) + sum (map size reachable)
+  where
+    ditches = makePath origin input
+    everything = coverBoxes ditches
+
+    noDitch = foldl (\remain next -> concatMap (subtractBox next) remain) [everything] ditches
+    neighbors region = [x | x <- noDitch, touch x region]
+    reachable = drop 1 (bfs neighbors (Dim 1 2 (Dim 1 2 Pt)))
+
+touch :: Box' 2 -> Box' 2 -> Bool
+touch (Dim y1 y2 (Dim x1 x2 Pt)) other =
+  isJust (intersectBox (Dim (y1-1) (y2+1) (Dim (x1-1) (x2+1) Pt)) other)
+
+dir2 :: Char -> D
+dir2 '0' = DR
+dir2 '1' = DD
+dir2 '2' = DL
+dir2 '3' = DU
+dir2 _   = error "bad direction digit"
+
+makePath :: Coord -> [(Int, D)] -> [Box' 2]
+makePath _ [] = []
+makePath here ((n, d) : xs) = toBox here n d : makePath (here + scaleCoord n (toVec d)) xs
+
+toVec :: D -> Coord
+toVec DD = south
+toVec DL = west
+toVec DR = east
+toVec DU = north
+
+toBox :: Coord -> Int -> D -> Box' 2
+toBox (C y x) n DD = Dim y (y + n) (Dim x (x + 1) Pt)
+toBox (C y x) n DR = Dim y (y + 1) (Dim x (x + n) Pt)
+toBox (C y x) n DU = Dim (y - n + 1) (y+1) (Dim x (x + 1) Pt)
+toBox (C y x) n DL = Dim y (y + 1) (Dim (x - n + 1) (x+1) Pt)