[2024][ruby][15.2]

2024/ruby/day_15.rb

@@ -1,4 +1,6 @@
-input = DATA.read.split("\n\n")
+input = DATA.read.gsub(
+  /[#O\.@]/, %w[ # ## O [] . .. @ @. ].each_slice(2).to_h
+).split("\n\n")
 
 map = {}
 input.shift.split("\n").each.with_index do |row, y|
@@ -29,8 +31,21 @@ def push(map, pos, move)
   case map.fetch(pospos, nil)
   when ?#
     raise Nope
-  when ?O
-    push(map, pospos, move)
+  when ?[, ?]
+    case move
+    when ?<, ?>
+      push(map, pospos, move)
+    when ?^, ?v
+      a = pospos
+      dx = {?[ => 1, ?] => -1}.fetch(map.fetch(pospos))
+      b = a.zip([0, dx]).map { _1 + _2 }
+      push_two(map, a, b, move).reverse.uniq.each do |pos, pospos|
+        map[pospos] = map.fetch(pos)
+        map.delete(pos)
+      end
+    else
+      fail
+    end
   when nil
   else
     fail
@@ -42,6 +57,28 @@ def push(map, pos, move)
   pospos
 end
 
+def push_two(map, a, b, move)
+  delta = DELTAS.fetch(move)
+  aa = a.zip(delta).map { _1 + _2 }
+  bb = b.zip(delta).map { _1 + _2 }
+
+  [[a, aa], [b, bb]].flat_map {|pos, pospos|
+    case map.fetch(pospos, nil)
+    when ?#
+      raise Nope
+    when ?[, ?]
+      a_ = pospos
+      dx = {?[ => 1, ?] => -1}.fetch(map.fetch(pospos))
+      b_ = a_.zip([0, dx]).map { _1 + _2 }
+      [[pos, pospos]] + push_two(map, a_, b_, move)
+    when nil
+      [[pos, pospos]]
+    else
+      fail
+    end
+  }
+end
+
 DELTAS = %w[ ^ v < > ].zip([[-1,0], [1,0], [0,-1], [0, 1]]).to_h
 movements = input.shift.gsub("\n", "").chars
 
@@ -52,15 +89,28 @@ movements.each do |move|
   end
 end
 
-pp map.select { _2 == ?O }.sum {|(y,x),_| 100 * y + x }
+# pp map.select { _2 == ?O }.sum {|(y,x),_| 100 * y + x }
+pp map.select { _2 == ?[ }.sum {|(y,x),_| 100 * y + x }
 
 __END__
-#######
-#...#.#
-#.....#
-#..OO@#
-#..O..#
-#.....#
-#######
+##########
+#..O..O.O#
+#......O.#
+#.OO..O.O#
+#..O@..O.#
+#O#..O...#
+#O..O..O.#
+#.OO.O.OO#
+#....O...#
+##########
 
-<vv<<^^<<^^
+<vv>^<v^>v>^vv^v>v<>v^v<v<^vv<<<^><<><>>v<vvv<>^v^>^<<<><<v<<<v^vv^v>^
+vvv<<^>^v^^><<>>><>^<<><^vv^^<>vvv<>><^^v>^>vv<>v<<<<v<^v>^<^^>>>^<v<v
+><>vv>v^v^<>><>>>><^^>vv>v<^^^>>v^v^<^^>v^^>v^<^v>v<>>v^v^<v>v^^<^^vv<
+<<v<^>>^^^^>>>v^<>vvv^><v<<<>^^^vv^<vvv>^>v<^^^^v<>^>vvvv><>>v^<<^^^^^
+^><^><>>><>^^<<^^v>>><^<v>^<vv>>v>>>^v><>^v><<<<v>>v<v<v>vvv>^<><<>^><
+^>><>^v<><^vvv<^^<><v<<<<<><^v<<<><<<^^<v<^^^><^>>^<v^><<<^>>^v<v^v<v^
+>^>>^v>vv>^<<^v<>><<><<v<<v><>v<^vv<<<>^^v^>^^>>><<^v>>v^v><^^>>^<>vv^
+<><^^>^^^<><vvvvv^v<v<<>^v<v>v<<^><<><<><<<^^<<<^<<>><<><^^^>^^<>^>v<>
+^^>vv<^v^v<vv>^<><v<^v>^^^>>>^^vvv^>vvv<>>>^<^>>>>>^<<^v>^vvv<>^<><<v>
+v^^>>><<^^<>>^v^<v^vv<>v^<<>^<^v^v><^<<<><<^<v><v<>vv>>v><v^<vv<>v^<<^