java: add solutions for year 2016, day 17

java/src/benchmark/java/com/github/saser/adventofcode/year2016/day17/BUILD.bazel

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+java_library(
+    name = "benchmark_library",
+    srcs = glob(["*.java"]),
+    deps = [
+        "@maven//:org_openjdk_jmh_jmh_core",
+        "//java/src/main/java/com/github/saser/adventofcode/year2016/day17:day17",
+    ],
+    plugins = ["//java/src/benchmark:annotation_processor"],
+    data = ["//inputs:2016/17"],
+)
+
+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/day17/Day17Benchmark.java

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+package com.github.saser.adventofcode.year2016.day17;
+
+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 Day17Benchmark {
+    private Reader input;
+
+    @Setup
+    public void setup() throws IOException {
+        var path = FileSystems.getDefault().getPath("inputs", "2016", "17");
+        var contents = Files.readString(path);
+        this.input = new StringReader(contents);
+    }
+
+    @Benchmark
+    public void part1() throws IOException {
+        Day17.part1(this.input);
+        this.input.reset();
+    }
+
+    @Benchmark
+    public void part2() throws IOException {
+        Day17.part2(this.input);
+        this.input.reset();
+    }
+}

java/src/main/java/com/github/saser/adventofcode/year2016/day17/BUILD.bazel

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+package(default_visibility = ["//visibility:public"])
+
+java_library(
+    name = "day17",
+    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/day17/Day17.java

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+package com.github.saser.adventofcode.year2016.day17;
+
+import java.io.BufferedReader;
+import java.io.Reader;
+import java.security.MessageDigest;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.Set;
+
+import com.github.saser.adventofcode.Result;
+import com.github.saser.adventofcode.geo.Point2D;
+import com.github.saser.adventofcode.tuple.Tuple2;
+
+public final class Day17 {
+    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 passcode = new BufferedReader(r).readLine();
+            var maze = new Maze(passcode);
+            var paths = maze.findVault(new Point2D(3, 3));
+            String answer;
+            if (part == 1) {
+                answer = paths.v1;
+            } else {
+                answer = Integer.toString(paths.v2.length());
+            }
+            return Result.ok(answer);
+        } catch (Exception e) {
+            e.printStackTrace();
+            return Result.err(e.getMessage());
+        }
+    }
+
+    private static class Maze {
+        public final String passcode;
+        private final MessageDigest md;
+
+        public Maze(String passcode) throws Exception {
+            this.passcode = passcode;
+            this.md = MessageDigest.getInstance("MD5");
+        }
+
+        public Tuple2<String, String> findVault(Point2D target) {
+            var queue = new LinkedList<Tuple2<Point2D, String>>();
+            queue.add(new Tuple2<>(new Point2D(0, 0), ""));
+            var shortestPath = "";
+            var longestPath = "";
+            while (!queue.isEmpty()) {
+                var tuple = queue.remove();
+                var point = tuple.v1;
+                var path = tuple.v2;
+                if (point.equals(target)) {
+                    if (shortestPath.equals("")) {
+                        shortestPath = path;
+                    }
+                    longestPath = path;
+                    continue;
+                }
+                for (var nextStep : this.nextSteps(path)) {
+                    var delta = new Point2D(0, 0);
+                    switch (nextStep) {
+                        case 'U':
+                            delta.y = -1;
+                            break;
+                        case 'D':
+                            delta.y = 1;
+                            break;
+                        case 'L':
+                            delta.x = -1;
+                            break;
+                        case 'R':
+                            delta.x = 1;
+                            break;
+                    }
+                    var nextPoint = point.plus(delta);
+                    if (nextPoint.x < 0 || nextPoint.x > 3 || nextPoint.y < 0 || nextPoint.y > 3) {
+                        continue;
+                    }
+                    queue.add(new Tuple2<>(nextPoint, path + nextStep));
+                }
+            }
+            return new Tuple2<>(shortestPath, longestPath);
+        }
+
+        private Set<Character> nextSteps(String path) {
+            var toHash = this.passcode + path;
+            var hash = Day17.hexString(md.digest((this.passcode + path).getBytes()));
+            var doors = "UDLR".toCharArray();
+            var openChars = "bcdef";
+            var openDoors = new HashSet<Character>();
+            for (var i = 0; i < 4; i++) {
+                if (openChars.contains(hash.substring(i, i + 1))) {
+                    openDoors.add(doors[i]);
+                }
+            }
+            return openDoors;
+        }
+    }
+
+    private static String hexString(byte[] bytes) {
+        final var HEX_CHARS = "0123456789abcdef".toCharArray();
+        var chars = new char[2 * bytes.length];
+        for (var i = 0; i < bytes.length; i++) {
+            var b = bytes[i] & 0xFF;
+            chars[2 * i] = HEX_CHARS[b >>> 4]; // upper nibble
+            chars[2 * i + 1] = HEX_CHARS[b & 0x0F]; // lower nibble;
+        }
+        return new String(chars);
+    }
+}

java/src/test/java/com/github/saser/adventofcode/year2016/day17/BUILD.bazel

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+java_test(
+    name = "test",
+    srcs = glob(["*.java"]),
+    test_class = "com.github.saser.adventofcode.year2016.day17.Day17Test",
+    deps = [
+        "@maven//:junit_junit",
+        "//java/src/main/java/com/github/saser/adventofcode:adventofcode",
+        "//java/src/main/java/com/github/saser/adventofcode/year2016/day17:day17",
+    ],
+    data = ["//inputs:2016/17"],
+)

java/src/test/java/com/github/saser/adventofcode/year2016/day17/Day17Test.java

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+package com.github.saser.adventofcode.year2016.day17;
+
+import java.io.FileReader;
+import java.io.IOException;
+import java.io.StringReader;
+
+import org.junit.Test;
+import org.junit.Assert;
+
+public class Day17Test {
+    @Test
+    public void part1Example1() {
+        var input = new StringReader("ihgpwlah");
+        var output = "DDRRRD";
+        var result = Day17.part1(input);
+        Assert.assertEquals("no error", "", result.error);
+        Assert.assertEquals("correct output", output, result.answer);
+    }
+
+    @Test
+    public void part1Example2() {
+        var input = new StringReader("kglvqrro");
+        var output = "DDUDRLRRUDRD";
+        var result = Day17.part1(input);
+        Assert.assertEquals("no error", "", result.error);
+        Assert.assertEquals("correct output", output, result.answer);
+    }
+
+    @Test
+    public void part1Example3() {
+        var input = new StringReader("ulqzkmiv");
+        var output = "DRURDRUDDLLDLUURRDULRLDUUDDDRR";
+        var result = Day17.part1(input);
+        Assert.assertEquals("no error", "", result.error);
+        Assert.assertEquals("correct output", output, result.answer);
+    }
+
+    @Test
+    public void part1Actual() throws IOException {
+        try (var input = new FileReader("inputs/2016/17")) {
+            var output = "DDRLRRUDDR";
+            var result = Day17.part1(input);
+            Assert.assertEquals("no error", "", result.error);
+            Assert.assertEquals("correct output", output, result.answer);
+        }
+    }
+
+    @Test
+    public void part2Example1() {
+        var input = new StringReader("ihgpwlah");
+        var output = "370";
+        var result = Day17.part2(input);
+        Assert.assertEquals("no error", "", result.error);
+        Assert.assertEquals("correct output", output, result.answer);
+    }
+
+    @Test
+    public void part2Example2() {
+        var input = new StringReader("kglvqrro");
+        var output = "492";
+        var result = Day17.part2(input);
+        Assert.assertEquals("no error", "", result.error);
+        Assert.assertEquals("correct output", output, result.answer);
+    }
+
+    @Test
+    public void part2Example3() {
+        var input = new StringReader("ulqzkmiv");
+        var output = "830";
+        var result = Day17.part2(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/2016/17")) {
+            var output = "556";
+            var result = Day17.part2(input);
+            Assert.assertEquals("no error", "", result.error);
+            Assert.assertEquals("correct output", output, result.answer);
+        }
+    }
+}