Solve a few more puzzles.

day11.cr

@@ -0,0 +1,42 @@
+require "advent"
+require "./intcode_fibers.cr"
+
+painted_white = Set({Int64, Int64}).new
+color = {} of {Int64,Int64} => Int64
+color[{0_i64, 0_i64}] = 1_i64
+input, output = new_interpreter("", input(2019, 11).split(",").map &.to_i64)
+pos = {0_i64, 0_i64}
+facing = {0_i64, 1_i64}
+
+struct Tuple(*T)
+  def turn_left
+    {-self[1], self[0]}
+  end
+
+  def turn_right
+    turn_left.turn_left.turn_left
+  end
+
+  def add(other)
+    {self[0] + other[0], self[1] + other[1]}
+  end
+end
+
+loop do
+  c = color[pos]? || 0_i64
+  input.send c
+  break unless nc = output.receive
+  break unless turn = output.receive
+  color[pos] = nc
+  painted_white << pos if nc == 1
+  facing = (turn == 0 ? facing.turn_left : facing.turn_right)
+  pos = pos.add facing
+end
+
+6.times do |y|
+  y = - y
+  45.times do |x|
+    print (color[{x.to_i64, y.to_i64}]? == 1 ? '#' : ' ')
+  end
+  puts
+end