Added 2015 Day 13

src/main/java/com/belellou/kevin/advent/year0/Day0.java

@@ -20,7 +20,7 @@ protected Integer doSolveFirstStar(BufferedReader reader) {
     @DisableTest
     @Override
     public Integer getFirstStarSolution() {
-        return 0;
+        return 1;
     }
 
     @Override
@@ -31,6 +31,6 @@ protected Integer doSolveSecondStar(BufferedReader reader) {
     @DisableTest
     @Override
     public Integer getSecondStarSolution() {
-        return 0;
+        return 1;
     }
 }

src/main/java/com/belellou/kevin/advent/year2015/Day13.java

@@ -0,0 +1,141 @@
+package com.belellou.kevin.advent.year2015;
+
+import java.io.BufferedReader;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import org.jgrapht.Graph;
+import org.jgrapht.GraphPath;
+import org.jgrapht.alg.tour.HeldKarpTSP;
+import org.jgrapht.graph.DefaultWeightedEdge;
+import org.jgrapht.graph.SimpleDirectedWeightedGraph;
+import org.jgrapht.graph.SimpleWeightedGraph;
+
+import com.belellou.kevin.advent.generic.AbstractDaySolver;
+
+@SuppressWarnings("unused")
+public class Day13 extends AbstractDaySolver<Integer> {
+
+    private static final String GROUP_FIRST_GUEST = "firstGuest";
+    private static final String GROUP_ACTION = "action";
+    private static final String GROUP_AMOUNT = "amount";
+    private static final String GROUP_SECOND_GUEST = "secondGuest";
+
+    private static final Pattern PATTERN = Pattern.compile("^" +
+                                                                   "(?<" + GROUP_FIRST_GUEST + ">\\w+)" +
+                                                                   " would " +
+                                                                   "(?<" + GROUP_ACTION + ">\\w+)" +
+                                                                   " (?<" + GROUP_AMOUNT + ">\\d+)" +
+                                                                   " happiness units by sitting next to " +
+                                                                   "(?<" + GROUP_SECOND_GUEST + ">\\w+)." +
+                                                                   "$");
+
+    private static final String ACTION_GAIN = "gain";
+    private static final String ME = "Me";
+
+    public Day13() {
+        super(Day13.class);
+    }
+
+    private static void fillGraph(String line, Graph<String, DefaultWeightedEdge> graph) {
+        Matcher matcher = PATTERN.matcher(line);
+
+        if (!matcher.matches()) {
+            throw new IllegalArgumentException("Invalid line: " + line);
+        }
+
+        String firstGuest = matcher.group(GROUP_FIRST_GUEST);
+        boolean gainAction = matcher.group(GROUP_ACTION).equals(ACTION_GAIN);
+        int amount = Integer.parseInt(matcher.group(GROUP_AMOUNT));
+        String secondGuest = matcher.group(GROUP_SECOND_GUEST);
+
+        graph.addVertex(firstGuest);
+        graph.addVertex(secondGuest);
+        DefaultWeightedEdge edge = graph.addEdge(firstGuest, secondGuest);
+        graph.setEdgeWeight(edge, gainAction ? amount : -amount);
+    }
+
+    private static SimpleWeightedGraph<String, DefaultWeightedEdge> transformGraph(
+            SimpleDirectedWeightedGraph<String, DefaultWeightedEdge> graph) {
+        SimpleWeightedGraph<String, DefaultWeightedEdge> undirectedGraph = new SimpleWeightedGraph<>(
+                DefaultWeightedEdge.class);
+
+        graph.vertexSet().forEach(undirectedGraph::addVertex);
+
+        graph.edgeSet().forEach(edge -> {
+            double edgeWeight = graph.getEdgeWeight(edge);
+
+            String edgeSource = graph.getEdgeSource(edge);
+            String edgeTarget = graph.getEdgeTarget(edge);
+
+            if (undirectedGraph.containsEdge(edgeSource, edgeTarget)) {
+                return;
+            }
+
+            DefaultWeightedEdge returnEdge = graph.getEdge(edgeTarget, edgeSource);
+            double returnEdgeWeight = graph.getEdgeWeight(returnEdge);
+
+            DefaultWeightedEdge undirectedEdge = undirectedGraph.addEdge(edgeSource, edgeTarget);
+            undirectedGraph.setEdgeWeight(undirectedEdge, -(edgeWeight + returnEdgeWeight));
+        });
+
+        return undirectedGraph;
+    }
+
+    private static int findOptimalHamiltonianCycleDistance(
+            SimpleDirectedWeightedGraph<String, DefaultWeightedEdge> directedGraph) {
+        SimpleWeightedGraph<String, DefaultWeightedEdge> undirectedGraph = transformGraph(directedGraph);
+
+        GraphPath<String, DefaultWeightedEdge> tour = new HeldKarpTSP<String, DefaultWeightedEdge>().getTour(
+                undirectedGraph);
+
+        return (int) -tour.getWeight();
+    }
+
+    private static SimpleDirectedWeightedGraph<String, DefaultWeightedEdge> createGraphFromReader(
+            BufferedReader reader) {
+        SimpleDirectedWeightedGraph<String, DefaultWeightedEdge> directedGraph = new SimpleDirectedWeightedGraph<>(
+                DefaultWeightedEdge.class);
+
+        reader.lines().forEach(line -> fillGraph(line, directedGraph));
+        return directedGraph;
+    }
+
+    @Override
+    protected Integer doSolveFirstStar(BufferedReader reader) {
+        SimpleDirectedWeightedGraph<String, DefaultWeightedEdge> directedGraph = createGraphFromReader(reader);
+
+        return findOptimalHamiltonianCycleDistance(directedGraph);
+    }
+
+    @Override
+    public Integer getFirstStarSolution() {
+        return 664;
+    }
+
+    @Override
+    protected Integer doSolveSecondStar(BufferedReader reader) {
+        SimpleDirectedWeightedGraph<String, DefaultWeightedEdge> directedGraph = createGraphFromReader(reader);
+
+        directedGraph.addVertex(ME);
+
+        for (String vertex : directedGraph.vertexSet()) {
+            if (vertex.equals(ME)) {
+                continue;
+            }
+
+            DefaultWeightedEdge edge = directedGraph.addEdge(ME, vertex);
+            directedGraph.setEdgeWeight(edge, 0);
+
+            edge = directedGraph.addEdge(vertex, ME);
+            directedGraph.setEdgeWeight(edge, 0);
+        }
+
+        return findOptimalHamiltonianCycleDistance(directedGraph);
+    }
+
+    @Override
+    public Integer getSecondStarSolution() {
+        return 640;
+    }
+}

src/main/resources/2015/13/input.txt

@@ -0,0 +1,56 @@
+Alice would lose 2 happiness units by sitting next to Bob.
+Alice would lose 62 happiness units by sitting next to Carol.
+Alice would gain 65 happiness units by sitting next to David.
+Alice would gain 21 happiness units by sitting next to Eric.
+Alice would lose 81 happiness units by sitting next to Frank.
+Alice would lose 4 happiness units by sitting next to George.
+Alice would lose 80 happiness units by sitting next to Mallory.
+Bob would gain 93 happiness units by sitting next to Alice.
+Bob would gain 19 happiness units by sitting next to Carol.
+Bob would gain 5 happiness units by sitting next to David.
+Bob would gain 49 happiness units by sitting next to Eric.
+Bob would gain 68 happiness units by sitting next to Frank.
+Bob would gain 23 happiness units by sitting next to George.
+Bob would gain 29 happiness units by sitting next to Mallory.
+Carol would lose 54 happiness units by sitting next to Alice.
+Carol would lose 70 happiness units by sitting next to Bob.
+Carol would lose 37 happiness units by sitting next to David.
+Carol would lose 46 happiness units by sitting next to Eric.
+Carol would gain 33 happiness units by sitting next to Frank.
+Carol would lose 35 happiness units by sitting next to George.
+Carol would gain 10 happiness units by sitting next to Mallory.
+David would gain 43 happiness units by sitting next to Alice.
+David would lose 96 happiness units by sitting next to Bob.
+David would lose 53 happiness units by sitting next to Carol.
+David would lose 30 happiness units by sitting next to Eric.
+David would lose 12 happiness units by sitting next to Frank.
+David would gain 75 happiness units by sitting next to George.
+David would lose 20 happiness units by sitting next to Mallory.
+Eric would gain 8 happiness units by sitting next to Alice.
+Eric would lose 89 happiness units by sitting next to Bob.
+Eric would lose 69 happiness units by sitting next to Carol.
+Eric would lose 34 happiness units by sitting next to David.
+Eric would gain 95 happiness units by sitting next to Frank.
+Eric would gain 34 happiness units by sitting next to George.
+Eric would lose 99 happiness units by sitting next to Mallory.
+Frank would lose 97 happiness units by sitting next to Alice.
+Frank would gain 6 happiness units by sitting next to Bob.
+Frank would lose 9 happiness units by sitting next to Carol.
+Frank would gain 56 happiness units by sitting next to David.
+Frank would lose 17 happiness units by sitting next to Eric.
+Frank would gain 18 happiness units by sitting next to George.
+Frank would lose 56 happiness units by sitting next to Mallory.
+George would gain 45 happiness units by sitting next to Alice.
+George would gain 76 happiness units by sitting next to Bob.
+George would gain 63 happiness units by sitting next to Carol.
+George would gain 54 happiness units by sitting next to David.
+George would gain 54 happiness units by sitting next to Eric.
+George would gain 30 happiness units by sitting next to Frank.
+George would gain 7 happiness units by sitting next to Mallory.
+Mallory would gain 31 happiness units by sitting next to Alice.
+Mallory would lose 32 happiness units by sitting next to Bob.
+Mallory would gain 95 happiness units by sitting next to Carol.
+Mallory would gain 91 happiness units by sitting next to David.
+Mallory would lose 66 happiness units by sitting next to Eric.
+Mallory would lose 75 happiness units by sitting next to Frank.
+Mallory would lose 99 happiness units by sitting next to George.