Day 11

day11.groovy

@@ -0,0 +1,128 @@
+import groovy.transform.EqualsAndHashCode
+import groovy.transform.ToString;
+import groovy.transform.TupleConstructor;
+
+
+@EqualsAndHashCode
+@ToString
+@TupleConstructor
+class Pos {
+    final int x;
+    final int y;
+}
+
+class Image {
+    def arr;
+    def width;
+    def height;
+
+    Image(List<String> input) {
+        arr = input.join("").toCharArray();
+        width = input[0].size();
+        height = input.size();
+    }
+
+    def getAt(Pos pos) {
+        int arrpos = pos.x + pos.y * width;
+        return arr[arrpos];
+    }
+
+    def posOf(char c) {
+        return arr.findIndexValues { it == c }.collect {
+            new Pos(it % width as int, Math.floor(it / width) as int)
+        };
+    }
+
+    def emptyRows() {
+        def result = [];
+        for (int j = 0; j < height; j++) {
+            def isEmpty = true;
+            for (int i = 0; i < width; i++) {
+                if (this[new Pos(i, j)] != '.' as char) {
+                    isEmpty = false;
+                    break;
+                }
+            }
+            if (isEmpty) {
+                result << j;
+            }
+        }
+        return result;
+    }
+
+    def emptyCols() {
+        def result = [];
+        for (int i = 0; i < width; i++) {
+            def isEmpty = true;
+            for (int j = 0; j < height; j++) {
+                if (this[new Pos(i, j)] != '.' as char) {
+                    isEmpty = false;
+                    break;
+                }
+            }
+            if (isEmpty) {
+                result << i;
+            }
+        }
+        return result;
+    }
+
+    String toString() {
+        def result = "";
+        for (int y = 0; y < height; y++) {
+            for (int x = 0; x < width; x++) {
+                result += this[new Pos(x, y)];
+            }
+            result += "\n";
+        }
+        return result;
+    }
+}
+
+
+def pathBetween(Pos a, Pos b) {
+    def x0 = Math.min(a.x, b.x);
+    def x1 = Math.max(a.x, b.x);
+    def y0 = Math.min(a.y, b.y);
+    def y1 = Math.max(a.y, b.y);
+
+    def result = [];
+    result.addAll((x0..x1).collect { new Pos(it, y0) });
+    result.addAll((y0<..y1).collect { new Pos(x1, it) });
+    return result;
+}
+
+def galaxyDistancesSum(def image, int distance) {
+    def galaxies = image.posOf('#' as char);
+    def emptyRows = image.emptyRows();
+    def emptyCols = image.emptyCols();
+
+    def galaxyPairs = [];
+    def galaxyPairsDistances = [];
+    for (int a = 0; a < galaxies.size(); a++) {
+        for (int b = a + 1; b < galaxies.size(); b++) {
+            def ga = galaxies[a];
+            def gb = galaxies[b];
+            galaxyPairs = [ga, gb];
+
+            def path = pathBetween(ga, gb)[1..-1];
+            def pathAfterExpansion = path.collect {
+                if (emptyRows.contains(it.y) || emptyCols.contains(it.x)) {
+                    return distance;
+                } else {
+                    return 1;
+                }
+            }.inject(0 as BigInteger) { acc, it -> acc + it };
+            galaxyPairsDistances << pathAfterExpansion;
+        }
+    }
+    return galaxyPairsDistances.sum();
+}
+
+
+def input = new File("input/day11.txt").readLines();
+def image = new Image(input);
+// println(image);
+
+println(galaxyDistancesSum(image, 2));
+println(galaxyDistancesSum(image, 1000000));