Day 17

day17/Part1.hs

@@ -0,0 +1,30 @@
+module Part1 where
+
+import Commons
+import Data.Array (Ix(inRange), bounds, (!))
+import Data.Maybe (catMaybes)
+
+
+cleanAstarNext :: City -> [Node] -> [(Node, Int)]
+cleanAstarNext city = map (\ (c, d, n) -> ((c, d, n), city ! c))
+                      . filter (\ ((y, x), _, n) -> inRange (bounds city) (y, x) && n <= 3)
+
+astarNext :: City -> Node -> [(Node, Int)]
+astarNext city ((y, x), East, n) = cleanAstarNext city [((y - 1, x), North, 1),
+                                                        ((y + 1, x), South, 1),
+                                                        ((y, x + 1), East, n + 1)]
+astarNext city ((y, x), South, n) = cleanAstarNext city [((y + 1, x), South, n + 1),
+                                                         ((y, x + 1), East, 1),
+                                                         ((y, x - 1), West, 1)]
+astarNext city ((y, x), West, n) = cleanAstarNext city [((y - 1, x), North, 1),
+                                                        ((y + 1, x), South, 1),
+                                                        ((y, x - 1), West, n + 1)]
+astarNext city ((y, x), North, n) = cleanAstarNext city [((y - 1, x), North, n + 1),
+                                                         ((y, x + 1), East, 1),
+                                                         ((y, x - 1), West, 1)]
+
+applyAstar :: City -> Direction -> Int -> Maybe Int
+applyAstar city d n = astar ((1, 1), East, 0) (snd $ bounds city, d, n) (astarNext city) astarEstimation
+
+getAllAstar :: City -> [Int]
+getAllAstar city = catMaybes [applyAstar city d n | d <- [East, South], n <- [1..3]]