Tweak PMD ruleset

Author: SvenWoltmann

ruleset.xml

@@ -32,6 +32,12 @@
     </properties>
   </rule>
 
+  <rule ref="category/java/codestyle.xml/TooManyStaticImports">
+    <properties>
+      <property name="maximumStaticImports" value="10" /><!-- Default is 4, which is too low IMO. -->
+    </properties>
+  </rule>
+
   <rule ref="category/java/codestyle.xml/LongVariable">
     <properties>
       <property name="minimum" value="65" />            <!-- Default max is 16, which is not always enough for a descriptive name; allow longer variables. -->

src/main/java/eu/happycoders/adventofcode2022/day24/Day24Solver.java

@@ -0,0 +1,23 @@
+package eu.happycoders.adventofcode2022.day24;
+
+/**
+ * Advent of Code 2022 – Object-Oriented Solutions in Java.
+ *
+ * <p>Puzzle solver for day 24.
+ *
+ * @author <a href="mailto:sven@happycoders.eu">Sven Woltmann</a>
+ */
+class Day24Solver {
+
+  static int solveTask1(String input) {
+    ValleyMap valleyMap = PuzzleInputParser.parse(input);
+    ValleyWalker valleyWalker = new ValleyWalker(valleyMap);
+    return valleyWalker.findFastestPath(1);
+  }
+
+  static int solveTask2(String input) {
+    ValleyMap valleyMap = PuzzleInputParser.parse(input);
+    ValleyWalker valleyWalker = new ValleyWalker(valleyMap);
+    return valleyWalker.findFastestPath(3);
+  }
+}

src/main/java/eu/happycoders/adventofcode2022/day24/Main24.java

@@ -0,0 +1,46 @@
+package eu.happycoders.adventofcode2022.day24;
+
+/**
+ * Advent of Code 2022 – Object-Oriented Solutions in Java.
+ *
+ * <p>Main application for day 24.
+ *
+ * @author <a href="mailto:sven@happycoders.eu">Sven Woltmann</a>
+ */
+class Main24 {
+
+  private static final String INPUT =
+      """
+          #.########################################################################################################################
+          #.v^<>^^.<^^<v>v>>>.<^<<v.^>vv>>^<<<v>.v<^v^<v<<^<^^<^<^v><^vv.v^^.>^><vv><^<.<^v<>.v<v..^>><v>.vvv.v>^^<^>.<<^<^<^>v.^^<#
+          #.^^<v>><<v><vv<>..<>v<^v><<>><>v.>v.^^<<.v.^<^<vv><v<<v><<^<>^v>v>><>v..v^<^.v><>^>><v<<>v^<<v<v>v.v<v>><<v>^v<v^...<<<>#
+          #><vv>>v>v<^>^^^^vv^<v^<<v<>^<^.^^>^<^vv>^v>><<^^<.>^>v<^v<.v.^<^^v.<.>.<^>v^>.v>>^vv^v.>>>v<<<<v.^^v<^^<^><<<<.^>.>vvv>>#
+          #<.vv>.><<.<^v.>v^v>><v>><<^vv>^v^>.><v>>><^><v<v^^vv>.v^^<v>vv<>v>^v.>>v^>..v<>^v.^>><.vv><^...<>^^>v>vvv>^<^<><v>v<^^^<#
+          #>^.^>vvv>vv>^^vv>v^^v>vv>v^v>^<v>>vvvv^>.v^<v^><^>vvv<>vv<^v<.<^v^>^vv^<><>.^.^>><<^^>^<v^>>>>v><<v^^>^^>>v^v.<^vv^<^v<>#
+          #><^>><vv^vvv.v><v<>^v>^<<<^^<><^<<v<>^<<v><<<v>><v<^^<vv<.>^v>^<v>.>v>>^^>^>><>.<<v<^><>>>^.<vv>.^^<.^^>>v.><<v<>><>v^><#
+          #>>^.<<v.^v>^^v.>v.vv^<<.v<v<..<<v^^>^v.><>v<^^<<.>v>v>v>^v>.<>v<><<^v><^>><^v>v^v>^vvv>>>..>^>>.><v><>.^^v.><<vv<.v>^^<.#
+          #>vv>^^.<>^v<^<<v^>v<^^v><>>>>v^vv>v<^v^><><^.<v^>.<^.v^>><vv>>vvv>^v<<<><vv<v^<<>v>>^v>^^^>^v><^^>^^^<<^^<v<<v<v>^^^<^>>#
+          #>.v^<<.vv<^v>^>>v<>v^v^^v^v<^^<<..<<^v<<<<^<v>^>.<>v<v<v<.<.v>vv^>><^.<.v<^<^v><v<v>.v.><<^>>v^.^vv.vv^.>^^>vv<>^..v>^v<#
+          #..v.>^><<>..<>.<^<<v>^^^^><<><<vv><^>v>^v<vv>v><vv.^<.<<<<v^v<>^^^vv>.>>>v^v<v<^.<v<<^.v<><<>>v<<<.>>v.^^>^^.>.<.>vv>^>>#
+          #>^^vv<<><<v<^.v>>v>^^^v^<v.^><<<<<v^v>v<<^v..^<.vv.^v>vvv>^v<..v<><<^<<vv<>>>>^>^^<>^<^<^^.vv>>^>^>^v^>.<^.<<.>v^>vv<.^<#
+          #<v^vv>^^v>vv>^.^>v>v^v>vv.>>.>v^v^>.^v<^.>^<<<v.>^>^^<>vv<.<^^<^v<^><v^v^.^<><v^^v^>.<vv^>v^v<v^><>^<vv>v<><^v<v.<<^.>^>#
+          #<>^<^<v><^^.^^>..^^>v>>>>^v<.<>>.<^v^>vvvvv>^<<.><^<v<.v<^><^^>vv<^<^<>v>v<>^^v>>^^>>v<^^<v>v^^^vvv<<<<<>>>v>^v.<^^>^>^<#
+          #>.<^v<.<^v.v>^.>>><^<<^^<<.<>><>>>^vvv<v<v<<^^vv<<<^v^v^vv<^v>>^^vv.^>^.v^^^>>v^>.<>.^^>v^^^^><^^>^>>.v<v^<^>^v^>^<<<v<<#
+          #>><><.>v^<>^^>.^>^v>^.^<v><><>.<v<^v>>>>v.<>>.^vv>v.vv.><vv^v>^<>>v>vv.v>v>v<><>>>^..^v>^^><..^..^..^vvv>><>v<>v<^<<>v<<#
+          #<vv^vvv><>v^v.<^v^^v<.<>v<>.^v^<<^<><.^vv<>^>>.v<<><vv<^^<>>v^.^v><v^^<>v.v<.>^^v^<<<^^<<v<^^^<<<<>^^v>><><<><>v>v<v.>^>#
+          #.<.^>^>^>^v..v>^.<v<^<<<^vvv>vv><^^v^<.>>.^<.^^<<>>^><<>>^^.^<<^^><^v<.><>.<<<.vvv>>vv^v<^v<>vv<<^v^^<v.v^<<^>v^>v<><vv<#
+          #.vvvv>>^>^<..^>>^>vv^.^>^<<v>^^v>v>^<>.>vv<v^>>>^.^<<^>>^>^>vvv><vv^^<^.^^.<^^v.<v<>^<<<v^>><<.^^^^>^>>>v<<>>v>v<>v<v><.#
+          #<<vv.<v>^^v<.>>^>^<>^><.<v^><>>.^<v^v<<.v>>.<>.v>^>^v><><^<><<<v^<><<v^..^v^v>^.><>>>v^.^>vv<<^>v<><.^^v<>vv>v^v<><^>>><#
+          #><>^v>v<>><vv>>v<>^<v>v^^>^v^>^^<v>v>^^v><<^v>>vv<^><>^>^^>>v^^<^<v>.^>v^vv^<.v>^v^.v^><><>>v.v^vv^<v>^>^><v>^>^>v>^v..<#
+          #>v<^^<^>.<>v<v<.^vv^>>v><^^v<^^>>^>^<^^>>>^<v<^v<>v<^>v>^>v^v>^.<<v^>vv<^<.><^><<^>v><^<v>^<^v>v^>><^vvv^>>v>>vv>v^>^><<#
+          #<vvv<><^.>v.^><v<^^<v><^<vvv.^..v^>...v^><<^^><^>^^vv>^v>v^<v<<>^>^^..<^<<v><<>.><<>^vvvv>v^><.^^>>v>>>^>>^<^<^<v^>vvv>>#
+          #><<<^^.^<.^.^^<>^.vv^^^<v^<<<vv<<>^<v<^>>v^>>v<<v^^.v^<.vv<v<><<.v><<^>>v><.v><v>v^^v^v<^><vvvvv<^.<<>v^.<>^.^><>^v><>^<#
+          #<.<>.>v^><<>^^<<vv>^>^v>>>v>v><^v><v.>>^<>>.<vv<<<v<v^<<vv^<.v^^>vv>>^<^<v<v<<>vv.><v..>>>.>^v<<vv><v^^^vv^^<>^>v<^^>v.>#
+          #<>^^<>>^v>v<<>^.>>^^^<<v>^vv^<^<.<<<vv>>v>^^<^v><><>.<>.^><<^^^>^vv><>v.<>v<.<v>>><v.^>^>vv<v>^<v^<<v^v>v..>^^<^^.><>^><#
+          ########################################################################################################################.#""";
+
+  public static void main(String[] args) {
+    System.out.println(Day24Solver.solveTask1(INPUT));
+    System.out.println(Day24Solver.solveTask2(INPUT));
+  }
+}

src/main/java/eu/happycoders/adventofcode2022/day24/Position.java

@@ -0,0 +1,28 @@
+package eu.happycoders.adventofcode2022.day24;
+
+/**
+ * Advent of Code 2022 – Object-Oriented Solutions in Java.
+ *
+ * <p>A position on the valley map.
+ *
+ * @author <a href="mailto:sven@happycoders.eu">Sven Woltmann</a>
+ */
+@SuppressWarnings("PMD.ShortVariable") // x and y are OK!
+record Position(int column, int row) {
+
+  Position up() {
+    return new Position(column, row - 1);
+  }
+
+  Position down() {
+    return new Position(column, row + 1);
+  }
+
+  Position left() {
+    return new Position(column - 1, row);
+  }
+
+  Position right() {
+    return new Position(column + 1, row);
+  }
+}

src/main/java/eu/happycoders/adventofcode2022/day24/PuzzleInputParser.java

@@ -0,0 +1,29 @@
+package eu.happycoders.adventofcode2022.day24;
+
+/**
+ * Advent of Code 2022 – Object-Oriented Solutions in Java.
+ *
+ * <p>Parses the input text into the valley map of blizzards.
+ *
+ * @author <a href="mailto:sven@happycoders.eu">Sven Woltmann</a>
+ */
+class PuzzleInputParser {
+
+  static ValleyMap parse(String input) {
+    String[] lines = input.split("\\n");
+    int height = lines.length - 2;
+    int width = lines[0].length() - 2;
+
+    Tile[][] tiles = new Tile[height][width];
+
+    for (int row = 0; row < height; row++) {
+      String line = lines[row + 1];
+
+      for (int column = 0; column < width; column++) {
+        tiles[row][column] = Tile.of(line.charAt(column + 1));
+      }
+    }
+
+    return new ValleyMap(tiles);
+  }
+}

src/main/java/eu/happycoders/adventofcode2022/day24/Tile.java

@@ -0,0 +1,36 @@
+package eu.happycoders.adventofcode2022.day24;
+
+/**
+ * Advent of Code 2022 – Object-Oriented Solutions in Java.
+ *
+ * <p>A tile on the valley map.
+ *
+ * @author <a href="mailto:sven@happycoders.eu">Sven Woltmann</a>
+ */
+enum Tile {
+  CLEAR_GROUND('.'),
+  UP('^'),
+  DOWN('v'),
+  LEFT('<'),
+  RIGHT('>');
+
+  private final char symbol;
+
+  Tile(char symbol) {
+    this.symbol = symbol;
+  }
+
+  char symbol() {
+    return symbol;
+  }
+
+  static Tile of(char symbol) {
+    // No need to optimize for speed here, this is called only once when the map is parsed
+    for (Tile value : values()) {
+      if (value.symbol == symbol) {
+        return value;
+      }
+    }
+    throw new IllegalArgumentException("Unknown symbol: " + symbol);
+  }
+}

src/main/java/eu/happycoders/adventofcode2022/day24/ValleyMap.java

@@ -0,0 +1,156 @@
+package eu.happycoders.adventofcode2022.day24;
+
+import java.util.Arrays;
+
+/**
+ * Advent of Code 2022 – Object-Oriented Solutions in Java.
+ *
+ * <p>The valley map of blizzards.
+ *
+ * @author <a href="mailto:sven@happycoders.eu">Sven Woltmann</a>
+ */
+class ValleyMap {
+
+  private final int width;
+  private final int height;
+  private final Tile[][] tiles;
+  private final Position startPosition;
+  private final Position targetPosition;
+
+  ValleyMap(Tile[][] tiles) {
+    this.width = tiles[0].length;
+    this.height = tiles.length;
+    this.tiles = tiles;
+
+    this.startPosition = new Position(0, -1);
+    this.targetPosition = new Position(width - 1, height);
+  }
+
+  Position startPosition() {
+    return startPosition;
+  }
+
+  Position targetPosition() {
+    return targetPosition;
+  }
+
+  boolean contains(Position position) {
+    return position.column() >= 0
+        && position.column() < width
+        && position.row() >= 0
+        && position.row() < height;
+  }
+
+  boolean isBlizzardAtMinute(Position position, int minute) {
+    return isUpBlizzardAtMinute(position, minute)
+        || isDownBlizzardAtMinute(position, minute)
+        || isLeftBlizzardAtMinute(position, minute)
+        || isRightBlizzardAtMinute(position, minute);
+  }
+
+  private boolean isUpBlizzardAtMinute(Position position, int minute) {
+    return tiles[modulo(position.row() + minute, height)][position.column()] == Tile.UP;
+  }
+
+  private boolean isDownBlizzardAtMinute(Position position, int minute) {
+    return tiles[modulo(position.row() - minute, height)][position.column()] == Tile.DOWN;
+  }
+
+  private boolean isLeftBlizzardAtMinute(Position position, int minute) {
+    return tiles[position.row()][modulo(position.column() + minute, width)] == Tile.LEFT;
+  }
+
+  private boolean isRightBlizzardAtMinute(Position position, int minute) {
+    return tiles[position.row()][modulo(position.column() - minute, width)] == Tile.RIGHT;
+  }
+
+  private int modulo(int numerator, int denominator) {
+    int result = numerator % denominator;
+    if (result < 0) {
+      result += denominator;
+    }
+    return result;
+  }
+
+  @Override
+  public boolean equals(Object object) {
+    if (this == object) {
+      return true;
+    }
+
+    if (object == null || getClass() != object.getClass()) {
+      return false;
+    }
+
+    ValleyMap that = (ValleyMap) object;
+    return Arrays.deepEquals(tiles, that.tiles);
+  }
+
+  @Override
+  public int hashCode() {
+    return Arrays.deepHashCode(tiles);
+  }
+
+  @Override
+  public String toString() {
+    return toStringAtTime(0);
+  }
+
+  String toStringAtTime(int minute) {
+    StringBuilder result = new StringBuilder();
+
+    for (int row = 0; row < height; row++) {
+      for (int column = 0; column < width; column++) {
+        result.append(getSymbolAtMinute(new Position(column, row), minute));
+      }
+      result.append('\n');
+    }
+
+    return result.toString();
+  }
+
+  private char getSymbolAtMinute(Position position, int minute) {
+    boolean isUpBlizzard = isUpBlizzardAtMinute(position, minute);
+    boolean isDownBlizzard = isDownBlizzardAtMinute(position, minute);
+    boolean isLeftBlizzard = isLeftBlizzardAtMinute(position, minute);
+    boolean isRightBlizzard = isRightBlizzardAtMinute(position, minute);
+
+    int count = countBlizzards(isUpBlizzard, isDownBlizzard, isLeftBlizzard, isRightBlizzard);
+    if (count == 0) {
+      return Tile.CLEAR_GROUND.symbol();
+    } else if (count == 1) {
+      if (isUpBlizzard) {
+        return Tile.UP.symbol();
+      } else if (isDownBlizzard) {
+        return Tile.DOWN.symbol();
+      } else if (isLeftBlizzard) {
+        return Tile.LEFT.symbol();
+      } else {
+        return Tile.RIGHT.symbol();
+      }
+    } else {
+      return (char) ('0' + count);
+    }
+  }
+
+  private static int countBlizzards(
+      boolean isUpBlizzard,
+      boolean isDownBlizzard,
+      boolean isLeftBlizzard,
+      boolean isRightBlizzard) {
+    int count = 0;
+    if (isUpBlizzard) {
+      count++;
+    }
+    if (isDownBlizzard) {
+      count++;
+    }
+    if (isLeftBlizzard) {
+      count++;
+    }
+    if (isRightBlizzard) {
+      count++;
+    }
+    return count;
+  }
+}