make day 17 faster by simpler key in map

zebalu · Dec 17, 2023 · 136e421 · 136e421
1 parent 0d6350a
commit 136e421
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Showing 2 changed files with 17 additions and 19 deletions.
diff --git a/aoc2023/src/main/java/io/github/zebalu/aoc2023/days/Day17.java b/aoc2023/src/main/java/io/github/zebalu/aoc2023/days/Day17.java
@@ -7,17 +7,16 @@
 public class Day17 {
     public static void main(String[] args) {
         List<String> maze = readInput().lines().toList();
-        part1(maze);
-        part2(maze);
+        System.out.println(part1(maze));
+        System.out.println(part2(maze));
     }
 
-    private static void part1(List<String> maze) {
-        System.out.println(minHeatLoss(maze, 3, (a, b) -> true));
+    private static int part1(List<String> maze) {
+        return minHeatLoss(maze, 3, (a, b) -> true);
     }
 
-    private static void part2(List<String> maze) {
-        System.out
-                .println(minHeatLoss(maze, 10, (c, s) -> 4 <= s.straightLength() || s.pos().directionOf(c) == s.dir()));
+    private static int part2(List<String> maze) {
+        return minHeatLoss(maze, 10, (c, s) -> 4 <= s.straightLength() || s.pos().directionOf(c) == s.dir());
     }
 
     private static int minHeatLoss(List<String> maze, int maxLength, BiPredicate<Coord, State> nextFilter) {
@@ -26,7 +25,7 @@ private static int minHeatLoss(List<String> maze, int maxLength, BiPredicate<Coo
         Predicate<Coord> isValidCood = c -> 0 <= c.x() && 0 <= c.y() && c.x < width && c.y < height;
         Predicate<State> isValidState = s -> isValidCood.test(s.pos()) && s.straightLength() <= maxLength;
         Coord target = new Coord(width - 1, height - 1);
-        Map<PosStepDir, Integer> psdCost = new HashMap<>();
+        Map<Long, Integer> bestCost = new HashMap<>();
         Queue<State> queue = new PriorityQueue<>();
         queue.add(new State(new Coord(0, 0), 0, 0, Direction.EAST));
         while (!queue.isEmpty()) {
@@ -40,9 +39,9 @@ private static int minHeatLoss(List<String> maze, int maxLength, BiPredicate<Coo
                 if (s.pos().equals(target)) {
                     return s.heatLoss;
                 }
-                var psd = PosStepDir.of(s);
-                if (!psdCost.containsKey(psd) || s.heatLoss < psdCost.get(psd)) {
-                    psdCost.put(psd, s.heatLoss);
+                var costKey = s.toKey();
+                if (!bestCost.containsKey(costKey) || s.heatLoss < bestCost.get(costKey)) {
+                    bestCost.put(costKey, s.heatLoss);
                     queue.add(s);
                 }
             }
@@ -96,8 +95,7 @@ Direction directionOf(Coord coord) {
 
     private record State(Coord pos, int straightLength, int heatLoss, Direction dir) implements Comparable<State> {
 
-        private static final Comparator<State> COMPARATOR = Comparator.comparingLong(State::heatLoss)
-                .thenComparingInt(State::straightLength);
+        private static final Comparator<State> COMPARATOR = Comparator.comparingLong(State::heatLoss).thenComparingInt(State::straightLength);
 
         @Override
         public int compareTo(State o) {
@@ -110,12 +108,10 @@ int nextStraight(Coord c) {
             }
             return 1;
         }
-
-    }
-
-    private record PosStepDir(Coord pos, int steps, Direction dir) {
-        static PosStepDir of(State state) {
-            return new PosStepDir(state.pos, state.straightLength, state.dir);
+
+        long toKey() {
+            return 0L+pos.x()*1_000_000L+pos.y()*1_000L+straightLength*10L+dir.ordinal();
         }
+
     }
 }
diff --git a/aoc2023/src/main/java/io/github/zebalu/aoc2023/main/App.java b/aoc2023/src/main/java/io/github/zebalu/aoc2023/main/App.java
@@ -28,6 +28,7 @@
 import io.github.zebalu.aoc2023.days.Day14;
 import io.github.zebalu.aoc2023.days.Day15;
 import io.github.zebalu.aoc2023.days.Day16;
+import io.github.zebalu.aoc2023.days.Day17;
 
 public class App {
 
@@ -59,6 +60,7 @@ public static void main(String[] args) {
         exec(new DisplayData(14, "Parabolic Reflector Dish", Day14::main));
         exec(new DisplayData(15, "Lens Library", Day15::main));
         exec(new DisplayData(16, "The Floor Will Be Lava", Day16::main));
+        exec(new DisplayData(17, "Clumsy Crucible", Day17::main));
         Instant end = Instant.now();
         System.out.println("so far:\t"+Duration.between(start, end).toMillis()+" ms...");
     }