Add day 10 and day 9 solutions.

day10.cr

@@ -0,0 +1,57 @@
+require "./common.cr"
+
+lines = File.read("day10_input").split "\n"
+lines.pop
+
+points = [] of Tuple(Int64, Int64, Int64, Int64)
+
+REGEX = /position=<\s*(-?\d+),\s*(-?\d+)> velocity=<\s*(-?\d+), \s*(-?\d+)>/
+lines.map(&.match(REGEX)).each do |match|
+  match = match.not_nil!
+  points << { match[1].to_i64, match[2].to_i64, match[3].to_i64, match[4].to_i64 }  
+end
+
+def max_distance(points)
+  points.product(points).max_of do |left, right|
+    (left[0] - right[0]).abs + (left[1] - right[1]).abs
+  end
+end
+
+def simulate(points, multiplier = 1)
+  points.size.times do |index|
+    old = points[index]
+    points[index] = { old[0] + multiplier * old[2], old[1] + multiplier * old[3], old[2], old[3] }
+  end
+end
+
+def print_message(points)
+  max_x = points.max_of &.[0]
+  min_x = points.min_of &.[0]
+  max_y = points.max_of &.[1]
+  min_y = points.min_of &.[1]
+
+  (max_y - min_y + 2).times do |yoff|
+    (max_x - min_x + 2).times do |xoff|
+      x = min_x + xoff - 1
+      y = min_y + yoff - 1
+      if points.any? { |point| (point[0] == x) && (point[1] == y) }
+        STDOUT << '▩'
+      else
+        STDOUT << '.'
+      end
+    end
+    puts
+  end
+end
+
+d1 = max_distance(points)
+simulate(points)
+d2 = max_distance(points)
+times = (d2 / (d2 - d1)).abs - 10
+simulate(points, times)
+
+20.times do |i|
+  simulate(points, multiplier = 1)
+  print_message(points)
+  puts "^ #{times + 1 + i + 1}"
+end

day9.cr

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+require "./common.cr"
+
+lines = File.read("day9_input").split "\n"
+lines.pop
+
+players = 463
+last_points = 400
+
+marbles = [ 0 ]
+scores = Array(Int32).new(players, 0)
+player = 0
+pos = 0
+
+(last_points).times do |i|
+  i = i + 1
+  if (i % 23 == 0)
+    delete_at = (pos - 7 - marbles.size) % marbles.size
+
+    puts "current: #{i}"
+    puts "popping: #{marbles[delete_at]}"
+    scores[player] += i
+    scores[player] += marbles[delete_at]
+
+    pos = delete_at
+    marbles.delete_at delete_at
+  else
+    at = (pos + 2) % marbles.size
+    marbles.insert at, i
+    pos = marbles.index(i).not_nil!
+  end
+  
+  puts marbles
+  player = (player + 1) % players
+end
+
+puts scores.max