java/2016/13: add solution for part 2

Author: saser

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

@@ -2,8 +2,9 @@
 
 import java.io.BufferedReader;
 import java.io.Reader;
-import java.util.HashSet;
+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;
@@ -26,28 +27,35 @@ private static Result solve(Reader r, int part) {
             var from = new Point2D(1, 1);
             var target = new Point2D(31, 39);
             var steps = Day13.steps(from, target, favorite);
-            return Result.ok(Integer.toString(steps));
+            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 int steps(Point2D from, Point2D target, int favorite) {
+    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 HashSet<Point2D>();
+        var visited = new HashMap<Point2D, Integer>();
         while (!queue.isEmpty()) {
             var tuple = queue.remove();
             var point = tuple.v1;
             var steps = tuple.v2;
-            if (point.equals(target)) {
-                return steps;
-            }
-            if (visited.contains(point)) {
+            if (visited.containsKey(point)) {
                 continue;
             }
-            visited.add(point);
+            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)),
@@ -63,7 +71,7 @@ private static int steps(Point2D from, Point2D target, int favorite) {
                 }
             }
         }
-        return 0;
+        return visited;
     }
 
     private static boolean isWall(Point2D point, int favorite) {

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

@@ -17,22 +17,13 @@ public void part1Actual() throws IOException {
         }
     }
 
-    // @Test
-    // public void part2Example() {
-    //     var input = new StringReader("");
-    //     var output = "";
-    //     var result = Day13.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/2016/13")) {
-    //         var output = "";
-    //         var result = Day13.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/2016/13")) {
+             var output = "124";
+             var result = Day13.part2(input);
+             Assert.assertEquals("no error", "", result.error);
+             Assert.assertEquals("correct output", output, result.answer);
+         }
+     }
 }