Solved Day 17 (2015) - No Such Thing as Too Much

Author: SimonBaars

src/main/java/com/sbaars/adventofcode/year15/days/Day17.java

@@ -1,23 +1,59 @@
 package com.sbaars.adventofcode.year15.days;
 
 import com.sbaars.adventofcode.year15.Day2015;
+import java.util.*;
+import java.util.stream.Collectors;
 
 public class Day17 extends Day2015 {
- public Day17() {
- super(17);
- }
-
- public static void main(String[] args) {
- new Day17().printParts();
- }
-
- @Override
- public Object part1() {
- return "";
- }
-
- @Override
- public Object part2() {
- return "";
- }
+
+ private static final int TARGET_LITERS = 150;
+ private final List<Integer> containers = new ArrayList<>();
+
+ public Day17() {
+ super(17);
+ parseInput();
+ }
+
+ public static void main(String[] args) {
+ Day17 day = new Day17();
+ day.printParts();
+ new com.sbaars.adventofcode.network.Submit().submit(day.part1(), 2015, 17, 1);
+ }
+
+ private void parseInput() {
+ Arrays.stream(day().split("\n"))
+ .map(String::trim)
+ .filter(s -> !s.isEmpty())
+ .map(Integer::parseInt)
+ .forEach(containers::add);
+ }
+
+ @Override
+ public Object part1() {
+ return findCombinations(0, 0, new boolean[containers.size()]);
+ }
+
+ @Override
+ public Object part2() {
+ return 0; // Implement in next part
+ }
+
+ private int findCombinations(int index, int currentSum, boolean[] used) {
+ if (currentSum == TARGET_LITERS) {
+ return 1;
+ }
+ if (currentSum > TARGET_LITERS || index >= containers.size()) {
+ return 0;
+ }
+
+ // Don't use current container
+ int withoutCurrent = findCombinations(index + 1, currentSum, used);
+
+ // Use current container
+ used[index] = true;
+ int withCurrent = findCombinations(index + 1, currentSum + containers.get(index), used);
+ used[index] = false;
+
+ return withoutCurrent + withCurrent;
+ }
 }