2015 Day 17

Author: dapitch666

src/main/java/org/anne/aoc2015/Day17.java

@@ -0,0 +1,55 @@
+package org.anne.aoc2015;
+
+import org.anne.common.Day;
+
+import java.util.List;
+
+public class Day17 extends Day {
+    public static void main(String[] args) {
+        new Day17().run();
+    }
+
+    @Override
+    public void execute() {
+        setName("No Such Thing as Too Much");
+        List<Integer> input = readFileAsInts();
+        setPart1(part1(input, 150));
+        setPart2(part2(input, 150));
+    }
+
+    public static int part1(List<Integer> input, int target) {
+        return findNbCombinations(input, target, false);
+    }
+
+    public static int part2(List<Integer> input, int target) {
+        return findNbCombinations(input, target, true);
+    }
+
+    private static int findNbCombinations(List<Integer> input, int target, boolean usingMinContainers) {
+        int minContainers = Integer.MAX_VALUE;
+        int count = 0;
+
+        for (int i = 0; i < (1 << input.size()); i++) {
+            int sum = 0;
+            int numContainers = 0;
+
+            for (int j = 0; j < input.size(); j++) {
+                if ((i & (1 << j)) > 0) {
+                    sum += input.get(j);
+                    numContainers++;
+                }
+            }
+
+            if (sum == target) {
+                if (usingMinContainers && numContainers < minContainers) {
+                    minContainers = numContainers;
+                    count = 1;
+                } else if (!usingMinContainers || numContainers == minContainers) {
+                    count++;
+                }
+            }
+        }
+
+        return count;
+    }
+}

src/test/java/org/anne/aoc2015/Day17Test.java

@@ -0,0 +1,23 @@
+package org.anne.aoc2015;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class Day17Test {
+
+    List<Integer> input = List.of(20, 15, 10, 5, 5);
+
+    @Test
+    void testPart1() {
+        assertEquals(4, Day17.part1(input, 25));
+    }
+
+    @Test
+    void testPart2() {
+        assertEquals(3, Day17.part2(input, 25));
+    }
+}