Day 9 - Part 1

2022-12-09 15:23:38 +01:00
parent e50555fe8b
commit 9bd3d62eec
6 changed files with 2206 additions and 10 deletions
--- a/test/Day9Spec.hs
+++ b/test/Day9Spec.hs
@@ -0,0 +1,79 @@
+{-# LANGUAGE QuasiQuotes #-}
+
+module Day9Spec (spec) where
+
+import Control.Arrow ((>>>))
+import Day9
+import Test.Hspec
+import Text.Heredoc
+import Data.List (sort)
+
+testInput :: String
+testInput =
+  [str|R 4
+                |U 4
+                |L 3
+                |D 1
+                |R 4
+                |D 1
+                |L 5
+                |R 2
+                |]
+
+expectedPositions :: [(Int, Int)]
+expectedPositions = sort [
+              (2,4),(3,4),
+                    (3,3),(4,3),
+        (1,2),(2,2),(3,2),(4,2),
+                          (4,1),
+  (0,0),(1,0),(2,0),(3,0)
+  ]
+
+spec :: Spec
+spec =
+  describe "Day9" $ do
+    describe "Part1" $ do
+      it "parses the instructions" $ do
+        parseMovements testInput
+          `shouldBe` [ right 4,
+                       up 4,
+                       left 3,
+                       down 1,
+                       right 4,
+                       down 1,
+                       left 5,
+                       right 2
+                     ]
+      it "moves a step" $ do
+        step (0, 0) (Step (1, 1)) `shouldBe` (1, 1)
+        step (0, 0) (Step (1, 0)) `shouldBe` (1, 0)
+        step (1, 0) (Step (-1, 0)) `shouldBe` (0, 0)
+        step (0, 1) (Step (0, -1)) `shouldBe` (0, 0)
+      it "normalizes movement" $ do
+        normalizeMovement still `shouldBe` []
+        normalizeMovement (left 1) `shouldBe` [Step (-1, 0)]
+        normalizeMovement (right 1) `shouldBe` [Step (1, 0)]
+        normalizeMovement (up 1) `shouldBe` [Step (0, 1)]
+        normalizeMovement (down 2) `shouldBe` [Step (0, -1), Step (0, -1)]
+      it "follows the head" $ do
+        follow (1, 0) (0, 0) `shouldBe` Step (0, 0)
+        follow (0, 1) (0, 0) `shouldBe` Step (0, 0)
+        follow (1, 1) (0, 0) `shouldBe` Step (0, 0)
+        follow (2, 1) (0, 0) `shouldBe` Step (1, 1)
+        follow (1, 2) (0, 0) `shouldBe` Step (1, 1)
+        follow (2, 2) (0, 0) `shouldBe` Step (1, 1)
+        follow (4, 2) (3, 0) `shouldBe` Step (1, 1)
+      it "moves around and records tail position" $ do
+        let positions = parseMovements
+                >>> concatMap normalizeMovement
+                >>> recordPositions
+                >>> sort
+                $ testInput
+        length positions `shouldBe` 13
+        positions `shouldBe` expectedPositions
+      it "solves the riddle" $ do
+        input <- readFile "ressources/day09-input"
+        putStrLn "Day9"
+        let movements = parseMovements input
+        let positions = concatMap normalizeMovement >>> recordPositions >>> length $ movements
+        positions `shouldBe` 5878