Solve AoC 2018 Day 25 Part 1 & 2

README.md

@@ -24,9 +24,9 @@ To run all solutions, simply run `./gradlew run`. If you want to run the solutio
 | 2021    | Kotlin ![Kotlin](img/kotlin.png)                                                               |         0 ⭐ | [aoc2021](https://github.com/Gentleman1983/aoc2021)                                |
 | 2020    | Kotlin ![Kotlin](img/kotlin.png)                                                               |         0 ⭐ | [aoc2020](https://github.com/Gentleman1983/advent-of-code/tree/main/aoc2020)       |
 | 2019    | JAVA ![JAVA](img/java.png)                                                                     |         0 ⭐ | [aoc2019](https://github.com/Gentleman1983/advent-of-code/tree/main/aoc2019)       |
-| 2018    | JAVA ![JAVA](img/java.png), Kotlin ![Kotlin](img/kotlin.png)                                   |        48 ⭐ | [aoc2018](https://github.com/Gentleman1983/advent-of-code/tree/main/aoc2018)       |
+| 2018    | JAVA ![JAVA](img/java.png), Kotlin ![Kotlin](img/kotlin.png)                                   |        50 ⭐ | [aoc2018](https://github.com/Gentleman1983/advent-of-code/tree/main/aoc2018)       |
 | 2017    | JAVA ![JAVA](img/java.png), Scala ![Scala](img/scala.png)                                      |        50 ⭐ | [aoc2017](https://github.com/Gentleman1983/advent-of-code/tree/main/aoc2017)       |
 | 2016    | JAVA ![JAVA](img/java.png), Kotlin ![Kotlin](img/kotlin.png), Groovy ![Groovy](img/groovy.png) |        50 ⭐ | [aoc2016](https://github.com/Gentleman1983/advent-of-code/tree/main/aoc2016)       |
 | 2015    | JAVA ![JAVA](img/java.png), Kotlin ![Kotlin](img/kotlin.png), Python ![Python](img/python.png) |        50 ⭐ | [aoc2015](https://github.com/Gentleman1983/advent-of-code/tree/main/aoc2015)       |
-| **SUM** |                                                                                                |   **300 ⭐** |                                                                                    |
+| **SUM** |                                                                                                |   **302 ⭐** |                                                                                    |
 

aoc2018/Day25.md

@@ -0,0 +1,120 @@
+# Day 25: Four-Dimensional Adventure
+The reindeer's symptoms are getting worse, and neither you nor the white-bearded man have a solution. At least the 
+reindeer has a warm place to rest: a small bed near where you're sitting.
+
+As you reach down, the reindeer looks up at you, accidentally bumping a button on your wrist-mounted device with its 
+nose in the process - a button labeled "**help**".
+
+"Hello, and welcome to the Time Travel Support Hotline! If you are lost in time and space, press 1. If you are trapped 
+in a time paradox, press 2. If you need help caring for a sick reindeer, press 3. If you--"
+
+**Beep**.
+
+A few seconds later, you hear a new voice. "Hello; please state the nature of your reindeer." You try to describe the 
+situation.
+
+"Just a moment, I think I can remotely run a diagnostic scan." A beam of light projects from the device and sweeps over 
+the reindeer a few times.
+
+"Okay, it looks like your reindeer is very low on magical energy; it should fully recover if we can fix that. Let me 
+check your timeline for a source.... Got one. There's actually a powerful source of magical energy about 1000 years 
+forward from you, and at roughly your position, too! It looks like... hot chocolate? Anyway, you should be able to 
+travel there to pick some up; just don't forget a mug! Is there anything else I can help you with today?"
+
+You explain that your device isn't capable of going forward in time. "I... see. That's tricky. Well, according to this 
+information, your device should have the necessary hardware to open a small portal and send some hot chocolate back to 
+you. You'll need a list of **fixed points in spacetime**; I'm transmitting it to you now."
+
+"You just need to align your device to the constellations of fixed points so that it can lock on to the destination and 
+open the portal. Let me look up how much hot chocolate that breed of reindeer needs."
+
+"It says here that your particular reindeer is-- this can't be right, it says there's only one like that in the 
+universe! But THAT means that you're--" You disconnect the call.
+
+The list of fixed points in spacetime (your puzzle input) is a set of four-dimensional coordinates. To align your 
+device, acquire the hot chocolate, and save the reindeer, you just need to find the **number of constellations** of 
+points in the list.
+
+Two points are in the same **constellation** if their manhattan distance apart is **no more than 3** or if they can form 
+a chain of points, each a manhattan distance no more than 3 from the last, between the two of them. (That is, if a point 
+is close enough to a constellation, it "joins" that constellation.) For example:
+```
+0,0,0,0
+3,0,0,0
+0,3,0,0
+0,0,3,0
+0,0,0,3
+0,0,0,6
+9,0,0,0
+12,0,0,0
+```
+In the above list, the first six points form a single constellation: 
+
+`0,0,0,0` is exactly distance `3` from the next four, and the point at `0,0,0,6` is connected to the others by being `3` 
+away from `0,0,0,3`, which is already in the constellation. The bottom two points, `9,0,0,0` and `12,0,0,0` are in a 
+separate constellation because no point is close enough to connect them to the first constellation. So, in the above 
+list, the number of constellations is **`2`**. (If a point at `6,0,0,0` were present, it would connect `3,0,0,0` and 
+`9,0,0,0`, merging all of the points into a single giant constellation instead.)
+
+In this example, the number of constellations is `4`:
+```
+-1,2,2,0
+0,0,2,-2
+0,0,0,-2
+-1,2,0,0
+-2,-2,-2,2
+3,0,2,-1
+-1,3,2,2
+-1,0,-1,0
+0,2,1,-2
+3,0,0,0
+```
+In this one, it's `3`:
+```
+1,-1,0,1
+2,0,-1,0
+3,2,-1,0
+0,0,3,1
+0,0,-1,-1
+2,3,-2,0
+-2,2,0,0
+2,-2,0,-1
+1,-1,0,-1
+3,2,0,2
+```
+Finally, in this one, it's `8`:
+```
+1,-1,-1,-2
+-2,-2,0,1
+0,2,1,3
+-2,3,-2,1
+0,2,3,-2
+-1,-1,1,-2
+0,-2,-1,0
+-2,2,3,-1
+1,2,2,0
+-1,-2,0,-2
+```
+The portly man nervously strokes his white beard. It's time to get that hot chocolate.
+
+**How many constellations are formed by the fixed points in spacetime**?
+
+# Part Two
+A small glowing portal opens above the mug you prepared and just enough hot chocolate streams in to fill it. You suspect 
+the reindeer has never encountered hot chocolate before, but seems to enjoy it anyway. You hope it works.
+
+It's time to start worrying about that **integer underflow in time itself** you 
+[set up a few days ago](https://adventofcode.com/2018/day/21). You check the status of the device: "Insufficient chronal 
+energy for activation. Energy required: **50 stars**."
+
+The reindeer bumps the device with its nose.
+
+"Energy required: **49 stars**."
+
+You have enough stars to **[Trigger the Underflow]**.
+
+You use all **fifty stars** to activate the underflow. As you begin to fall, the little reindeer looks up at you; its 
+nose begins to glow red.
+
+You go back in time so far that you wrap around and end up back in your own time again! Oddly, history books contain 
+some new details that you don't recognize...

aoc2018/README.md

@@ -34,7 +34,7 @@ For more information see https://adventofcode.com [2018](https://adventofcode.co
 | 22      | ⭐ ![Kotlin](../img/kotlin.png)                          | ⭐ ![Kotlin](../img/kotlin.png)                          |
 | 23      | ⭐ ![JAVA](../img/java.png)                              | ⭐ ![Kotlin](../img/kotlin.png)                          |
 | 24      | ⭐ ![JAVA](../img/java.png)                              | ⭐ ![JAVA](../img/java.png)                              |
-| 25      | ❌ ![JAVA](../img/java.png)                              | ❌ ![JAVA](../img/java.png)                              |
-| **SUM** | **24 ⭐**                                                | **24 ⭐**                                                |
+| 25      | ⭐ ![JAVA](../img/java.png)                              | ⭐ ![JAVA](../img/java.png)                              |
+| **SUM** | **25 ⭐**                                                | **25 ⭐**                                                |
 
-Total: 48 ⭐
+Total: 50 ⭐

aoc2018/aoc2018-java/src/main/java/de/havox_design/aoc2018/day25/FourDimensionalAdventure.java

@@ -0,0 +1,68 @@
+package de.havox_design.aoc2018.day25;
+
+import de.havox_design.aoc.utils.java.AoCFunctionality;
+
+import java.util.List;
+
+public class FourDimensionalAdventure implements AoCFunctionality {
+    private final List<Position4d> positions;
+
+    public FourDimensionalAdventure(String fileName) {
+        PositionParser parser = new PositionParser();
+        List<String> input = readData(fileName);
+
+        positions = input
+                .stream()
+                .map(parser::parseLine)
+                .toList();
+    }
+
+    public static long processTask1(String fileName) {
+        FourDimensionalAdventure instance = new FourDimensionalAdventure(fileName);
+        return instance.processTask1();
+    }
+
+    public static String processTask2(String fileName) {
+        FourDimensionalAdventure instance = new FourDimensionalAdventure(fileName);
+        return instance.processTask2();
+    }
+
+    public long processTask1() {
+        int sizeMinus1 = positions.size() - 1;
+        Integer[] parents = new Integer[positions.size()];
+        int constellations = positions.size();
+
+        for (int i = 0; i < sizeMinus1; i++) {
+            for (int j = i + 1; j < positions.size(); j++) {
+                if (positions.get(i).manhattanDistance(positions.get(j)) <= 3) {
+                    int iParent = getParent(parents, i);
+                    int jParent = getParent(parents, j);
+
+                    if (iParent != jParent) {
+                        parents[jParent] = iParent;
+                        constellations--;
+                    }
+                }
+            }
+        }
+
+        return constellations;
+    }
+
+    public String processTask2() {
+        return "Merry XMas!!!";
+    }
+
+    private int getParent(final Integer[] parents, int i) {
+        Integer parent = parents[i];
+
+        if (parent == null) {
+            return i;
+        }
+
+        parent = getParent(parents, parent);
+        parents[i] = parent;
+
+        return parent;
+    }
+}

aoc2018/aoc2018-java/src/main/java/de/havox_design/aoc2018/day25/Position4d.java

@@ -0,0 +1,10 @@
+package de.havox_design.aoc2018.day25;
+
+public record Position4d(int x, int y, int z, int s) {
+    public int manhattanDistance(Position4d other) {
+        return Math.abs(x - other.x) +
+                Math.abs(y - other.y) +
+                Math.abs(z - other.z) +
+                Math.abs(s - other.s);
+    }
+}

aoc2018/aoc2018-java/src/main/java/de/havox_design/aoc2018/day25/PositionParser.java

@@ -0,0 +1,23 @@
+package de.havox_design.aoc2018.day25;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class PositionParser {
+    private static final String POSITION_PATTERN = "^(?<x>-?\\d+),\\s*(?<y>-?\\d+),\\s*(?<z>-?\\d+),\\s*(?<s>-?\\d+)$";
+
+    public Position4d parseLine(String line) {
+        Pattern pattern = Pattern.compile(POSITION_PATTERN);
+        Matcher matcher = pattern.matcher(line);
+
+        if (matcher.matches()) {
+            int x = Integer.parseInt(matcher.group("x").trim());
+            int y = Integer.parseInt(matcher.group("y").trim());
+            int z = Integer.parseInt(matcher.group("z").trim());
+            int s = Integer.parseInt(matcher.group("s").trim());
+
+            return new Position4d(x, y, z, s);
+        }
+        throw new IllegalArgumentException("Expected the input '" + line + "' to match pattern '" + POSITION_PATTERN + "'.");
+    }
+}