Add solutions to days 10 and 11

day11.cr

@@ -0,0 +1,64 @@
+require "advent"
+INPUT = input(2020, 11).lines.map(&.chars) 
+
+abstract class Search
+  def search(current, x, y, dx, dy)
+    x, y = x + dx, y + dy
+    return 0 if y < 0 || y >= current.size
+    return 0 if x < 0 || x >= current[y].size
+    search_impl(current,x,y,dx,dy)
+  end
+
+  abstract def search_impl(current, x, y, dx, dy)
+end
+
+class FirstSearch < Search
+  def search_impl(current, x, y, dx, dy)
+    return current[y][x] == '#' ? 1 : 0
+  end
+end
+
+class SecondSearch < Search
+  def search_impl(current, x, y, dx, dy)
+    return 1 if current[y][x] == '#'
+    return 0 if current[y][x] == 'L'
+    return search(current, x, y, dx, dy)
+  end
+end
+
+DIRS = [{-1,-1}, {-1, 0}, {-1, 1}, {0, -1}, {0, 1}, {1, -1}, {1, 0}, {1,1}]
+
+def step(current, step, check, n)
+  current.each_with_index do |row, y|
+    row.each_with_index do |seat, x|
+      step[y][x] = current[y][x]
+      count = DIRS.sum do |dx, dy|
+        check.search(current, x, y, dx, dy)
+      end
+      step[y][x] = 'L' if seat == '#' && count >= n
+      step[y][x] = '#' if seat == 'L' && count == 0
+    end
+  end
+  {step, current}
+end
+
+def run(input, search, n)
+  current = input
+  step = input.clone
+  loop do
+    current, step = step(current, step, search, n)
+    break if current.zip_with(step) { |l, r| l == r }.all?
+  end
+  current.sum(&.count(&.==('#')))
+end
+
+def part1(input)
+  run(input, FirstSearch.new, 4)
+end
+
+def part2(input)
+  run(input, SecondSearch.new, 5)
+end
+
+puts part1(INPUT.clone)
+puts part2(INPUT.clone)