java/2016/17: add solution for part 2

Author: saser

java/src/main/java/com/github/saser/adventofcode/year2016/day17/Day17.java

@@ -24,8 +24,14 @@ private static Result solve(Reader r, int part) {
         try {
             var passcode = new BufferedReader(r).readLine();
             var maze = new Maze(passcode);
-            var path = maze.findVault(new Point2D(3, 3));
-            return Result.ok(path);
+            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());
@@ -41,15 +47,21 @@ public Maze(String passcode) throws Exception {
             this.md = MessageDigest.getInstance("MD5");
         }
 
-        public String findVault(Point2D target) {
+        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)) {
-                    return path;
+                    if (shortestPath.equals("")) {
+                        shortestPath = path;
+                    }
+                    longestPath = path;
+                    continue;
                 }
                 for (var nextStep : this.nextSteps(path)) {
                     var delta = new Point2D(0, 0);
@@ -74,7 +86,7 @@ public String findVault(Point2D target) {
                     queue.add(new Tuple2<>(nextPoint, path + nextStep));
                 }
             }
-            throw new Error("unreachable");
+            return new Tuple2<>(shortestPath, longestPath);
         }
 
         private Set<Character> nextSteps(String path) {

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

@@ -45,22 +45,40 @@ public void part1Actual() throws IOException {
         }
     }
 
-    // @Test
-    // public void part2Example() {
-    //     var input = new StringReader("");
-    //     var output = "";
-    //     var result = Day17.part2(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 part2Actual() throws IOException {
-    //     try (var input = new FileReader("inputs/2016/17")) {
-    //         var output = "";
-    //         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);
+        }
+    }
 }