Solve day 15 2015 part 2: Science for Hungry People

Author: SimonBaars

src/main/java/com/sbaars/adventofcode/year15/days/Day15.java

@@ -20,6 +20,7 @@ public static void main(String[] args) {
  Day15 day = new Day15();
  day.printParts();
  new com.sbaars.adventofcode.network.Submit().submit(day.part1(), 2015, 15, 1);
+ new com.sbaars.adventofcode.network.Submit().submit(day.part2(), 2015, 15, 2);
  }
 
  private void parseInput() {
@@ -45,7 +46,7 @@ public Object part1() {
 
  @Override
  public Object part2() {
- return 0; // Implement in next part
+ return findBestScoreWithCalories(500);
  }
 
  private long findBestScore() {
@@ -56,6 +57,15 @@ private long findBestScore() {
  .orElse(0);
  }
 
+ private long findBestScoreWithCalories(int targetCalories) {
+ return generateCombinations(TOTAL_TEASPOONS, ingredients.size())
+ .stream()
+ .filter(amounts -> calculateCalories(amounts) == targetCalories)
+ .mapToLong(this::calculateScore)
+ .max()
+ .orElse(0);
+ }
+
  private List<List<Integer>> generateCombinations(int total, int parts) {
  List<List<Integer>> result = new ArrayList<>();
  generateCombinationsHelper(total, parts, new ArrayList<>(), result);
@@ -100,6 +110,14 @@ private long calculateScore(List<Integer> amounts) {
  return (long) capacity * durability * flavor * texture;
  }
 
+ private int calculateCalories(List<Integer> amounts) {
+ int calories = 0;
+ for (int i = 0; i < ingredients.size(); i++) {
+ calories += ingredients.get(i).calories * amounts.get(i);
+ }
+ return calories;
+ }
+
  private static class Ingredient {
  private final String name;
  private final int capacity;