@@ -8,6 +8,7 @@ public class Day17 extends Day2015 {
88
99 private static final int TARGET_LITERS = 150 ;
1010 private final List <Integer > containers = new ArrayList <>();
11+ private final Map <Integer , Integer > containerCountMap = new HashMap <>();
1112
1213 public Day17 () {
1314 super (17 );
@@ -18,6 +19,7 @@ public static void main(String[] args) {
1819 Day17 day = new Day17 ();
1920 day .printParts ();
2021 new com .sbaars .adventofcode .network .Submit ().submit (day .part1 (), 2015 , 17 , 1 );
22+ new com .sbaars .adventofcode .network .Submit ().submit (day .part2 (), 2015 , 17 , 2 );
2123 }
2224
2325 private void parseInput () {
@@ -30,28 +32,34 @@ private void parseInput() {
3032
3133 @ Override
3234 public Object part1 () {
33- return findCombinations (0 , 0 , new boolean [containers .size ()]);
35+ return findCombinations (0 , 0 , new boolean [containers .size ()], 0 );
3436 }
3537
3638 @ Override
3739 public Object part2 () {
38- return 0 ; // Implement in next part
40+ containerCountMap .clear ();
41+ findCombinations (0 , 0 , new boolean [containers .size ()], 0 );
42+ int minContainers = containerCountMap .keySet ().stream ()
43+ .min (Integer ::compareTo )
44+ .orElse (0 );
45+ return containerCountMap .get (minContainers );
3946 }
4047
41- private int findCombinations (int index , int currentSum , boolean [] used ) {
48+ private int findCombinations (int index , int currentSum , boolean [] used , int containerCount ) {
4249 if (currentSum == TARGET_LITERS ) {
50+ containerCountMap .merge (containerCount , 1 , Integer ::sum );
4351 return 1 ;
4452 }
4553 if (currentSum > TARGET_LITERS || index >= containers .size ()) {
4654 return 0 ;
4755 }
4856
4957 // Don't use current container
50- int withoutCurrent = findCombinations (index + 1 , currentSum , used );
58+ int withoutCurrent = findCombinations (index + 1 , currentSum , used , containerCount );
5159
5260 // Use current container
5361 used [index ] = true ;
54- int withCurrent = findCombinations (index + 1 , currentSum + containers .get (index ), used );
62+ int withCurrent = findCombinations (index + 1 , currentSum + containers .get (index ), used , containerCount + 1 );
5563 used [index ] = false ;
5664
5765 return withoutCurrent + withCurrent ;
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