java: add solutions for year 2016, day 13

java/src/benchmark/java/com/github/saser/adventofcode/year2016/day13/BUILD.bazel

@@ -0,0 +1,19 @@
+java_library(
+    name = "benchmark_library",
+    srcs = glob(["*.java"]),
+    deps = [
+        "@maven//:org_openjdk_jmh_jmh_core",
+        "//java/src/main/java/com/github/saser/adventofcode/year2016/day13:day13",
+    ],
+    plugins = ["//java/src/benchmark:annotation_processor"],
+    data = ["//inputs:2016/13"],
+)
+
+java_binary(
+    name = "benchmark",
+    main_class = "org.openjdk.jmh.Main",
+    runtime_deps = [
+        "@maven//:org_openjdk_jmh_jmh_core",
+        ":benchmark_library",
+    ],
+)

java/src/benchmark/java/com/github/saser/adventofcode/year2016/day13/Day13Benchmark.java

@@ -0,0 +1,49 @@
+package com.github.saser.adventofcode.year2016.day13;
+
+import java.io.IOException;
+import java.io.Reader;
+import java.io.StringReader;
+import java.nio.file.Files;
+import java.nio.file.FileSystems;
+import java.util.concurrent.TimeUnit;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.TearDown;
+import org.openjdk.jmh.annotations.Warmup;
+
+@BenchmarkMode(Mode.AverageTime)
+@Fork(1)
+@Measurement(iterations = 1, time = 1)
+@OutputTimeUnit(TimeUnit.MILLISECONDS)
+@State(Scope.Benchmark)
+@Warmup(iterations = 5, time = 1)
+public class Day13Benchmark {
+    private Reader input;
+
+    @Setup
+    public void setup() throws IOException {
+        var path = FileSystems.getDefault().getPath("inputs", "2016", "13");
+        var contents = Files.readString(path);
+        this.input = new StringReader(contents);
+    }
+
+    @Benchmark
+    public void part1() throws IOException {
+        Day13.part1(this.input);
+        this.input.reset();
+    }
+
+    @Benchmark
+    public void part2() throws IOException {
+        Day13.part2(this.input);
+        this.input.reset();
+    }
+}

java/src/main/java/com/github/saser/adventofcode/geo/Point2D.java

@@ -1,5 +1,7 @@
 package com.github.saser.adventofcode.geo;
 
+import java.util.Objects;
+
 public final class Point2D {
     public int x;
     public int y;
@@ -23,6 +25,31 @@ public void add(Point2D other) {
         this.y += other.y;
     }
 
+    public Point2D plus(Point2D other) {
+        var copy = this.clone();
+        copy.add(other);
+        return copy;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Point2D point2D = (Point2D) o;
+        return x == point2D.x &&
+                y == point2D.y;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(x, y);
+    }
+
+    @Override
+    public String toString() {
+        return String.format("(%d, %d)", this.x, this.y);
+    }
+
     @Override
     public Point2D clone() {
         return new Point2D(this);

java/src/main/java/com/github/saser/adventofcode/tuple/BUILD.bazel

@@ -0,0 +1,6 @@
+package(default_visibility = ["//visibility:public"])
+
+java_library(
+    name = "tuple",
+    srcs = glob(["*.java"]),
+)

java/src/main/java/com/github/saser/adventofcode/tuple/Tuple2.java

@@ -0,0 +1,36 @@
+package com.github.saser.adventofcode.tuple;
+
+import java.util.Objects;
+
+public class Tuple2<T1, T2> {
+    public final T1 v1;
+    public final T2 v2;
+
+    public Tuple2(T1 v1, T2 v2) {
+        this.v1 = v1;
+        this.v2 = v2;
+    }
+
+    @Override
+    public String toString() {
+        var s = new String[] {
+                this.v1.toString(),
+                this.v2.toString(),
+        };
+        return "(" + String.join(", ", s) + ")";
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Tuple2<?, ?> tuple2 = (Tuple2<?, ?>) o;
+        return v1.equals(tuple2.v1) &&
+                v2.equals(tuple2.v2);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(v1, v2);
+    }
+}

java/src/main/java/com/github/saser/adventofcode/tuple/Tuple3.java

@@ -0,0 +1,40 @@
+package com.github.saser.adventofcode.tuple;
+
+import java.util.Objects;
+
+public class Tuple3<T1, T2, T3> {
+    public final T1 v1;
+    public final T2 v2;
+    public final T3 v3;
+
+    public Tuple3(T1 v1, T2 v2, T3 v3) {
+        this.v1 = v1;
+        this.v2 = v2;
+        this.v3 = v3;
+    }
+
+    @Override
+    public String toString() {
+        var s = new String[] {
+                this.v1.toString(),
+                this.v2.toString(),
+                this.v3.toString(),
+        };
+        return "(" + String.join(", ", s) + ")";
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        Tuple3<?, ?, ?> tuple3 = (Tuple3<?, ?, ?>) o;
+        return v1.equals(tuple3.v1) &&
+                v2.equals(tuple3.v2) &&
+                v3.equals(tuple3.v3);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(v1, v2, v3);
+    }
+}

java/src/main/java/com/github/saser/adventofcode/year2016/day13/BUILD.bazel

@@ -0,0 +1,11 @@
+package(default_visibility = ["//visibility:public"])
+
+java_library(
+    name = "day13",
+    srcs = glob(["*.java"]),
+    deps = [
+        "//java/src/main/java/com/github/saser/adventofcode/geo:geo",
+        "//java/src/main/java/com/github/saser/adventofcode/tuple:tuple",
+        "//java/src/main/java/com/github/saser/adventofcode:adventofcode",
+    ],
+)

java/src/main/java/com/github/saser/adventofcode/year2016/day13/Day13.java

@@ -0,0 +1,82 @@
+package com.github.saser.adventofcode.year2016.day13;
+
+import java.io.BufferedReader;
+import java.io.Reader;
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.Map;
+
+import com.github.saser.adventofcode.Result;
+import com.github.saser.adventofcode.geo.Point2D;
+import com.github.saser.adventofcode.tuple.Tuple2;
+
+public final class Day13 {
+    public static Result part1(Reader r) {
+        return solve(r, 1);
+    }
+
+    public static Result part2(Reader r) {
+        return solve(r, 2);
+    }
+
+    private static Result solve(Reader r, int part) {
+        try {
+            var br = new BufferedReader(r);
+            var input = br.readLine();
+            var favorite = Integer.parseInt(input);
+            var from = new Point2D(1, 1);
+            var target = new Point2D(31, 39);
+            var steps = Day13.steps(from, target, favorite);
+            if (part == 1) {
+                return Result.ok(Integer.toString(steps.get(target)));
+            }
+            var within50 = steps.values()
+                    .stream()
+                    .filter((length) -> length <= 50)
+                    .count();
+            return Result.ok(Long.toString(within50));
+        } catch (Exception e) {
+            e.printStackTrace();
+            return Result.err(e.getMessage());
+        }
+    }
+
+    private static Map<Point2D, Integer> steps(Point2D from, Point2D target, int favorite) {
+        var queue = new LinkedList<Tuple2<Point2D, Integer>>();
+        queue.add(new Tuple2<>(from, 0));
+        var visited = new HashMap<Point2D, Integer>();
+        while (!queue.isEmpty()) {
+            var tuple = queue.remove();
+            var point = tuple.v1;
+            var steps = tuple.v2;
+            if (visited.containsKey(point)) {
+                continue;
+            }
+            visited.put(point, steps);
+            if (point.equals(target)) {
+                break;
+            }
+            var neighbors = new Point2D[] {
+                    point.plus(new Point2D(1, 0)),
+                    point.plus(new Point2D(-1, 0)),
+                    point.plus(new Point2D(0, 1)),
+                    point.plus(new Point2D(0, -1)),
+            };
+            for (var neighbor : neighbors) {
+                if (neighbor.x < 0 || neighbor.y < 0) {
+                    continue;
+                }
+                if (!Day13.isWall(neighbor, favorite)) {
+                    queue.add(new Tuple2<>(neighbor, steps + 1));
+                }
+            }
+        }
+        return visited;
+    }
+
+    private static boolean isWall(Point2D point, int favorite) {
+        var x = point.x;
+        var y = point.y;
+        return Integer.bitCount((x*x + 3*x + 2*x*y + y + y*y) + favorite) % 2 == 1;
+    }
+}

java/src/test/java/com/github/saser/adventofcode/year2016/day13/BUILD.bazel

@@ -0,0 +1,11 @@
+java_test(
+    name = "test",
+    srcs = glob(["*.java"]),
+    test_class = "com.github.saser.adventofcode.year2016.day13.Day13Test",
+    deps = [
+        "@maven//:junit_junit",
+        "//java/src/main/java/com/github/saser/adventofcode:adventofcode",
+        "//java/src/main/java/com/github/saser/adventofcode/year2016/day13:day13",
+    ],
+    data = ["//inputs:2016/13"],
+)

java/src/test/java/com/github/saser/adventofcode/year2016/day13/Day13Test.java

@@ -0,0 +1,29 @@
+package com.github.saser.adventofcode.year2016.day13;
+
+import java.io.FileReader;
+import java.io.IOException;
+
+import org.junit.Test;
+import org.junit.Assert;
+
+public class Day13Test {
+    @Test
+    public void part1Actual() throws IOException {
+        try (var input = new FileReader("inputs/2016/13")) {
+            var output = "92";
+            var result = Day13.part1(input);
+            Assert.assertEquals("no error", "", result.error);
+            Assert.assertEquals("correct output", output, result.answer);
+        }
+    }
+
+     @Test
+     public void part2Actual() throws IOException {
+         try (var input = new FileReader("inputs/2016/13")) {
+             var output = "124";
+             var result = Day13.part2(input);
+             Assert.assertEquals("no error", "", result.error);
+             Assert.assertEquals("correct output", output, result.answer);
+         }
+     }
+}