Add solution for Advent of code 2015, Day 2

Author: andrei-punko

src/main/java/by/andd3dfx/game/IWasToldThereWouldBeNoMath.java

@@ -0,0 +1,74 @@
+package by.andd3dfx.game;
+
+import lombok.SneakyThrows;
+import org.apache.commons.lang3.math.NumberUtils;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * <pre>
+ * --- Day 2: I Was Told There Would Be No Math ---
+ *
+ * The elves are running low on wrapping paper, and so they need to submit an order for more. They have a list of the dimensions (length l, width w, and height h) of each present, and only want to order exactly as much as they need.
+ *
+ * Fortunately, every present is a box (a perfect right rectangular prism), which makes calculating the required wrapping paper for each gift a little easier: find the surface area of the box, which is 2*l*w + 2*w*h + 2*h*l. The elves also need a little extra paper for each present: the area of the smallest side.
+ *
+ * For example:
+ *
+ *     A present with dimensions 2x3x4 requires 2*6 + 2*12 + 2*8 = 52 square feet of wrapping paper plus 6 square feet of slack, for a total of 58 square feet.
+ *     A present with dimensions 1x1x10 requires 2*1 + 2*10 + 2*10 = 42 square feet of wrapping paper plus 1 square foot of slack, for a total of 43 square feet.
+ *
+ * All numbers in the elves' list are in feet. How many total square feet of wrapping paper should they order?
+ * </pre>
+ *
+ * @see <a href="https://youtu.be/RRyUtaNnntI">Video solution</a>
+ */
+public class IWasToldThereWouldBeNoMath {
+
+    public static int calculate(List<String> dimensionsList) {
+        int result = 0;
+        for (var dimensions : dimensionsList) {
+            var dimensionStrings = dimensions.split("x");
+            var sortedDimensions = Arrays.stream(dimensionStrings).map(NumberUtils::toInt)
+                    .sorted()
+                    .toList();
+            result += fullArea(sortedDimensions) + areaOfSmallestSide(sortedDimensions);
+        }
+        return result;
+    }
+
+    private static int fullArea(List<Integer> dimension) {
+        return 2 * (dimension.get(0) * dimension.get(1)
+                + dimension.get(1) * dimension.get(2)
+                + dimension.get(2) * dimension.get(0));
+    }
+
+    private static int areaOfSmallestSide(List<Integer> dimension) {
+        return dimension.get(0) * dimension.get(1);
+    }
+
+    @SneakyThrows
+    public static void main(String[] args) {
+        var lines = read("/game/i-was-told-there-would-be-no-math.txt");
+        var result = calculate(lines);
+        System.out.println(result);
+    }
+
+    private static List<String> read(String filePathName) throws IOException {
+        InputStream inputStream = IWasToldThereWouldBeNoMath.class.getResourceAsStream(filePathName);
+        var result = new ArrayList<String>();
+        try (var br = new BufferedReader(new InputStreamReader(inputStream))) {
+            String line;
+            while ((line = br.readLine()) != null) {
+                result.add(line);
+            }
+        }
+        return result;
+    }
+}