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Day25.java
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Day25.java
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package com.sbaars.adventofcode.year23.days;
import com.sbaars.adventofcode.common.Pair;
import com.sbaars.adventofcode.common.map.ListMap;
import com.sbaars.adventofcode.year23.Day2023;
import java.util.*;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import static com.sbaars.adventofcode.common.map.ListMap.toListMap;
import static com.sbaars.adventofcode.util.DataMapper.readString;
import static java.util.Comparator.reverseOrder;
public class Day25 extends Day2023 {
public Day25() {
super(25);
}
public static void main(String[] args) {
new Day25().printParts();
}
public record Wiring(String comp, List<String> connectedTo) {
}
@Override
public Object part1() {
ListMap<String, String> connections = dayStream().map(s -> readString(s, "%s: %ls", " ", Wiring.class)).flatMap(w -> w.connectedTo.stream().map(c -> new Pair<>(w.comp, c))).flatMap(p -> Stream.of(p, p.flip())).collect(toListMap(Pair::a, Pair::b));
String randomNode = connections.keySet().stream().findFirst().orElseThrow();
var totalSize = dijkstra(connections, randomNode).size();
var allNodes = connections.values().stream().flatMap(Collection::stream).collect(Collectors.toSet());
record PathComponent(String label, AtomicInteger counter) implements Comparable<PathComponent> {
@Override
public int compareTo(PathComponent o) {
var c = Integer.compare(counter.get(), o.counter.get());
return c != 0 ? c : label.compareTo(o.label);
}
}
Map<String, PathComponent> pathComponents = new HashMap<>();
allNodes.forEach(s -> dijkstra(connections, s).forEach((k, v) -> {
var label = k.compareTo(v.node) < 0 ? k + " " + v.node : v.node + " " + k;
pathComponents.computeIfAbsent(label, t -> new PathComponent(t, new AtomicInteger())).counter.incrementAndGet();
}));
pathComponents.values().stream().sorted(reverseOrder()).limit(3L).map(PathComponent::label).map(s -> s.split(" ")).forEach(s -> {
connections.removeFrom(s[0], s[1]);
connections.removeFrom(s[1], s[0]);
});
var reducedSize = dijkstra(connections, randomNode).size();
return reducedSize * (totalSize - reducedSize);
}
public record ND(String node, int distance) implements Comparable<ND> {
@Override
public int compareTo(ND o) {
int d = Integer.compare(distance, o.distance);
return d != 0 ? d : node.compareTo(o.node);
}
}
@Override
public Object part2() {
return "That's all!";
}
public Map<String, ND> dijkstra(ListMap<String, String> nodes, String node) {
var queue = new PriorityQueue<ND>();
Set<String> visited = new HashSet<>();
Map<String, ND> distanceMap = new HashMap<>();
queue.add(new ND(node, 0));
while (!queue.isEmpty()) {
var current = queue.remove();
visited.add(current.node);
nodes.get(current.node).stream()
.filter(s -> !visited.contains(s))
.filter(s -> !distanceMap.containsKey(s) || distanceMap.get(s).distance > current.distance + 1)
.forEach(s -> {
distanceMap.put(s, new ND(current.node, current.distance + 1));
queue.add(new ND(s, current.distance + 1));
});
}
return distanceMap;
}
}