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1 | 1 | package com.sbaars.adventofcode.year15.days; |
2 | 2 |
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3 | 3 | import com.sbaars.adventofcode.year15.Day2015; |
| 4 | +import java.util.*; |
| 5 | +import java.util.regex.Matcher; |
| 6 | +import java.util.regex.Pattern; |
| 7 | +import java.util.stream.Collectors; |
4 | 8 |
|
5 | 9 | public class Day13 extends Day2015 { |
6 | | - public Day13() { |
7 | | - super(13); |
8 | | - } |
9 | | - |
10 | | - public static void main(String[] args) { |
11 | | - new Day13().printParts(); |
12 | | - } |
13 | | - |
14 | | - @Override |
15 | | - public Object part1() { |
16 | | - return ""; |
17 | | - } |
18 | | - |
19 | | - @Override |
20 | | - public Object part2() { |
21 | | - return ""; |
22 | | - } |
| 10 | + |
| 11 | + private final Map<String, Map<String, Integer>> happinessMap = new HashMap<>(); |
| 12 | + private final Set<String> people = new HashSet<>(); |
| 13 | + |
| 14 | + public Day13() { |
| 15 | + super(13); |
| 16 | + parseInput(); |
| 17 | + } |
| 18 | + |
| 19 | + public static void main(String[] args) { |
| 20 | + Day13 day = new Day13(); |
| 21 | + day.printParts(); |
| 22 | + new com.sbaars.adventofcode.network.Submit().submit(day.part1(), 2015, 13, 1); |
| 23 | + } |
| 24 | + |
| 25 | + private void parseInput() { |
| 26 | + Pattern pattern = Pattern.compile("(\\w+) would (gain|lose) (\\d+) happiness units by sitting next to (\\w+)\\."); |
| 27 | + Arrays.stream(day().split("\n")).forEach(line -> { |
| 28 | + Matcher matcher = pattern.matcher(line); |
| 29 | + if (matcher.find()) { |
| 30 | + String person1 = matcher.group(1); |
| 31 | + String person2 = matcher.group(4); |
| 32 | + int happiness = Integer.parseInt(matcher.group(3)); |
| 33 | + if (matcher.group(2).equals("lose")) { |
| 34 | + happiness = -happiness; |
| 35 | + } |
| 36 | + |
| 37 | + happinessMap.computeIfAbsent(person1, k -> new HashMap<>()).put(person2, happiness); |
| 38 | + people.add(person1); |
| 39 | + people.add(person2); |
| 40 | + } |
| 41 | + }); |
| 42 | + } |
| 43 | + |
| 44 | + @Override |
| 45 | + public Object part1() { |
| 46 | + List<String> peopleList = new ArrayList<>(people); |
| 47 | + return findMaxHappiness(peopleList); |
| 48 | + } |
| 49 | + |
| 50 | + @Override |
| 51 | + public Object part2() { |
| 52 | + return 0; // Implement in next part |
| 53 | + } |
| 54 | + |
| 55 | + private int findMaxHappiness(List<String> peopleList) { |
| 56 | + return generatePermutations(peopleList).stream() |
| 57 | + .mapToInt(this::calculateHappiness) |
| 58 | + .max() |
| 59 | + .orElse(0); |
| 60 | + } |
| 61 | + |
| 62 | + private Set<List<String>> generatePermutations(List<String> original) { |
| 63 | + if (original.isEmpty()) { |
| 64 | + Set<List<String>> result = new HashSet<>(); |
| 65 | + result.add(new ArrayList<>()); |
| 66 | + return result; |
| 67 | + } |
| 68 | + |
| 69 | + String firstElement = original.get(0); |
| 70 | + List<String> rest = original.subList(1, original.size()); |
| 71 | + Set<List<String>> permutations = generatePermutations(rest); |
| 72 | + Set<List<String>> newPermutations = new HashSet<>(); |
| 73 | + |
| 74 | + for (List<String> permutation : permutations) { |
| 75 | + for (int i = 0; i <= permutation.size(); i++) { |
| 76 | + List<String> newPermutation = new ArrayList<>(permutation); |
| 77 | + newPermutation.add(i, firstElement); |
| 78 | + newPermutations.add(newPermutation); |
| 79 | + } |
| 80 | + } |
| 81 | + return newPermutations; |
| 82 | + } |
| 83 | + |
| 84 | + private int calculateHappiness(List<String> arrangement) { |
| 85 | + int totalHappiness = 0; |
| 86 | + int size = arrangement.size(); |
| 87 | + |
| 88 | + for (int i = 0; i < size; i++) { |
| 89 | + String current = arrangement.get(i); |
| 90 | + String next = arrangement.get((i + 1) % size); |
| 91 | + |
| 92 | + totalHappiness += happinessMap.get(current).get(next); |
| 93 | + totalHappiness += happinessMap.get(next).get(current); |
| 94 | + } |
| 95 | + |
| 96 | + return totalHappiness; |
| 97 | + } |
23 | 98 | } |
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