1 files changed, 75 insertions, 0 deletions
diff --git a/Day11.cs b/Day11.cs
new file mode 100644
index 0000000..1c1e270
--- /dev/null
+++ b/Day11.cs
@@ -0,0 +1,75 @@
+using aoc2019.lib;
+using System;
+using System.Collections.Generic;
+using System.Drawing;
+using System.Linq;
+
+namespace aoc2019
+{
+    internal class Day11 : Day
+    {
+        public override int DayNumber => 11;
+
+        private IntCodeVM vm;
+        List<List<bool>> paintmap;
+        long x, y;
+        Direction heading;
+
+        public Day11()
+        {
+            vm = new IntCodeVM(Input.First());
+            paintmap = new List<List<bool>>();
+            x = 0; y = 0;
+            heading = Direction.Up;
+        }
+
+        enum Direction
+        {
+            Up, Down, Left, Right
+        }
+
+        private (long, long) DxDy()
+        {
+            return heading switch
+            {
+                Direction.Up => (0, 1),
+                Direction.Down => (0, -1),
+                Direction.Left => (-1, 0),
+                Direction.Right => (1, 0)
+            };
+        }
+
+        private void Turn(long direction)
+        {
+            switch (heading)
+            {
+                case Direction.Up:    heading = direction == 0 ? Direction.Left : Direction.Right; break;
+                case Direction.Down:  heading = direction == 0 ? Direction.Right : Direction.Left; break;
+                case Direction.Left:  heading = direction == 0 ? Direction.Down : Direction.Up; break;
+                case Direction.Right: heading = direction == 0 ? Direction.Up : Direction.Down; break;
+            }
+        }
+
+        public override string Part1()
+        {
+            vm.Reset();
+            vm.Run();
+            var output = vm.output.ToList();
+            long dx, dy;
+            for (var i = 0; i < output.Count; i += 2)
+            {
+                long color = output[i];
+                Turn(output[i + 1]);
+                paintmap[x][y] = color == 0;
+                (dx, dy) = DxDy();
+                x += dx; y += dy;
+            }
+            return $"{paintmap.Count(x => x != null)}";
+        }
+
+        public override string Part2()
+        {
+            return "";
+        }
+    }
+}