Day twenty

20/input

@@ -0,0 +1,141 @@
+#############################################################################################################################################
+#...#...###...#####...#...#.......#####.....#...#.........###...###...#.....#...#.......#.....#...#...###...#.......#...........#.....#.....#
+#.#.#.#.###.#.#####.#.#.#.#.#####.#####.###.#.#.#.#######.###.#.###.#.#.###.#.#.#.#####.#.###.#.#.#.#.###.#.#.#####.#.#########.#.###.#.###.#
+#.#.#.#.#...#...#...#.#.#.#.....#...#...#...#.#...#.......#...#.#...#.#.#...#.#.#...#...#...#...#...#.#...#.#...#...#.#.........#...#.#...#.#
+#.#.#.#.#.#####.#.###.#.#.#####.###.#.###.###.#####.#######.###.#.###.#.#.###.#.###.#.#####.#########.#.###.###.#.###.#.###########.#.###.#.#
+#.#.#.#.#.....#...#...#.#.#.....#...#...#.#...#.....#...###.#...#...#.#.#...#.#.###.#.#...#.....#.....#...#.#...#.....#.....#...#...#...#.#.#
+#.#.#.#.#####.#####.###.#.#.#####.#####.#.#.###.#####.#.###.#.#####.#.#.###.#.#.###.#.#.#.#####.#.#######.#.#.#############.#.#.#.#####.#.#.#
+#.#...#.......#.....#...#.#.....#...#...#.#.#...#.....#...#.#.#...#.#.#.#...#.#.#...#.#.#.#...#.#...#...#.#.#.#.............#.#...#.....#.#.#
+#.#############.#####.###.#####.###.#.###.#.#.###.#######.#.#.#.#.#.#.#.#.###.#.#.###.#.#.#.#.#.###.#.#.#.#.#.#.#############.#####.#####.#.#
+#.#...#...#...#...###.#...#...#.#...#...#...#...#...#.....#.#.#.#.#.#.#.#...#.#...#...#.#.#.#.#.#...#.#.#.#.#.#.....#...###...#.....#...#.#.#
+#.#.#.#.#.#.#.###.###.#.###.#.#.#.#####.#######.###.#.#####.#.#.#.#.#.#.###.#.#####.###.#.#.#.#.#.###.#.#.#.#.#####.#.#.###.###.#####.#.#.#.#
+#...#.#.#...#...#...#.#.#...#.#.#.#...#...#.....#...#...###.#.#.#.#.#...#...#.#.....#...#...#.#.#.....#...#...#...#.#.#...#...#.......#...#.#
+#####.#.#######.###.#.#.#.###.#.#.#.#.###.#.#####.#####.###.#.#.#.#.#####.###.#.#####.#######.#.###############.#.#.#.###.###.#############.#
+#...#.#.###...#.#...#.#.#...#.#.#.#.#.#...#...#...#.....#...#...#.#.....#...#.#.#...#.....#...#.#.....#.........#...#...#.....#...#...#.....#
+#.#.#.#.###.#.#.#.###.#.###.#.#.#.#.#.#.#####.#.###.#####.#######.#####.###.#.#.#.#.#####.#.###.#.###.#.###############.#######.#.#.#.#.#####
+#.#...#.#...#...#.....#...#.#.#.#.#.#.#...#...#...#.....#.......#.###...#...#.#...#...###.#.###.#.###.#.....#...#...###.#.......#...#...#...#
+#.#####.#.###############.#.#.#.#.#.#.###.#.#####.#####.#######.#.###.###.###.#######.###.#.###.#.###.#####.#.#.#.#.###.#.###############.#.#
+#.......#.........#.....#.#.#...#...#.###.#.#...#.....#...###...#.....#...###...#.....#...#...#...#...#...#...#...#.#...#.#...#...#...###.#.#
+#################.#.###.#.#.#########.###.#.#.#.#####.###.###.#########.#######.#.#####.#####.#####.###.#.#########.#.###.#.#.#.#.#.#.###.#.#
+#.................#.#...#.#.....#.....#...#...#...#...#...#...#.....#...###...#.#.....#.#...#.###...#...#...#.....#.#...#.#.#...#...#.....#.#
+#.#################.#.###.#####.#.#####.#########.#.###.###.###.###.#.#####.#.#.#####.#.#.#.#.###.###.#####.#.###.#.###.#.#.###############.#
+#.........#.........#...#.......#.###...#.........#...#.###...#.#...#.#...#.#...#.....#...#.#.#...#...#####...#...#.#...#...#.....#...#.....#
+#########.#.###########.#########.###.###.###########.#.#####.#.#.###.#.#.#.#####.#########.#.#.###.###########.###.#.#######.###.#.#.#.#####
+#.......#...#...#...#...#...#...#...#...#.........#...#.....#...#...#.#.#.#.....#...#...#...#...#...#...#...###.....#.#...#...###...#.#.#...#
+#.#####.#####.#.#.#.#.###.#.#.#.###.###.#########.#.#######.#######.#.#.#.#####.###.#.#.#.#######.###.#.#.#.#########.#.#.#.#########.#.#.#.#
+#.#...#.###...#...#...#...#...#...#.....#.........#.....#...###...#.#...#...###.#...#.#.#.....#...#...#.#.#...#...#...#.#...#.....#...#...#.#
+#.#.#.#.###.###########.#########.#######.#############.#.#####.#.#.#######.###.#.###.#.#####.#.###.###.#.###.#.#.#.###.#####.###.#.#######.#
+#...#.#.....#...#...#...###...###.......#.......#...#...#...#...#.#.......#.....#.#...#...###.#...#.#...#.#...#.#.#.#...#...#.#...#.#.....#.#
+#####.#######.#.#.#.#.#####.#.#########.#######.#.#.#.#####.#.###.#######.#######.#.#####.###.###.#.#.###.#.###.#.#.#.###.#.#.#.###.#.###.#.#
+###...#.......#...#...#...#.#.#.......#.#.......#.#.#.#.....#...#.###...#.#.......#.....#.....#...#.#...#.#.....#...#...#.#...#...#...###...#
+###.###.###############.#.#.#.#.#####.#.#.#######.#.#.#.#######.#.###.#.#.#.###########.#######.###.###.#.#############.#.#######.###########
+#...#...#.......#.......#.#.#.#...#...#.#.#...#...#.#.#.#.....#.#.#...#...#.....#...#...#.......###.#...#.#...........#...#.....#.....#.....#
+#.###.###.#####.#.#######.#.#.###.#.###.#.#.#.#.###.#.#.#.###.#.#.#.###########.#.#.#.###.#########.#.###.#.#########.#####.###.#####.#.###.#
+#...#.###.....#.#.......#...#.....#...#.#.#.#.#...#.#.#.#...#.#.#.#.......#.....#.#.#.#...#...#...#.#.#...#.........#.#.....###...#...#.#...#
+###.#.#######.#.#######.#############.#.#.#.#.###.#.#.#.###.#.#.#.#######.#.#####.#.#.#.###.#.#.#.#.#.#.###########.#.#.#########.#.###.#.###
+#...#.#.......#.......#...#.........#.#.#.#.#.#...#.#.#...#.#.#.#...#...#.#.#...#.#.#.#...#.#.#.#.#.#...#.....#...#.#.#.....#...#...#...#...#
+#.###.#.#############.###.#.#######.#.#.#.#.#.#.###.#.###.#.#.#.###.#.#.#.#.#.#.#.#.#.###.#.#.#.#.#.#####.###.#.#.#.#.#####.#.#.#####.#####.#
+#.....#.........#...#...#.#.###.....#...#.#.#.#...#.#...#.#.#.#...#.#.#.#.#.#.#.#.#.#.#...#.#.#.#.#.#...#...#...#...#.#...#.#.#...#...#.....#
+###############.#.#.###.#.#.###.#########.#.#.###.#.###.#.#.#.###.#.#.#.#.#.#.#.#.#.#.#.###.#.#.#.#.#.#.###.#########.#.#.#.#.###.#.###.#####
+#.....#.......#...#...#.#...#...#.......#...#...#.#.#...#...#...#.#...#...#.#.#.#.#.#.#...#.#.#.#.#.#.#.....#.......#...#...#.#...#.#...#...#
+#.###.#.#####.#######.#.#####.###.#####.#######.#.#.#.#########.#.#########.#.#.#.#.#.###.#.#.#.#.#.#.#######.#####.#########.#.###.#.###.#.#
+#...#.#.....#.#...#...#.......#...#.....#...###.#.#.#...###...#.#.........#.#.#...#...###...#.#.#.#.#.#.....#...#...#.....#...#.....#.....#.#
+###.#.#####.#.#.#.#.###########.###.#####.#.###.#.#.###.###.#.#.#########.#.#.###############.#.#.#.#.#.###.###.#.###.###.#.###############.#
+#...#.....#.#...#...#...#...#...###.......#...#.#.#.#...#...#...#...#.....#.#...#.............#.#.#.#...#...###.#...#...#.#.#.........#.....#
+#.#######.#.#########.#.#.#.#.###############.#.#.#.#.###.#######.#.#.#####.###.#.#############.#.#.#####.#####.###.###.#.#.#.#######.#.#####
+#.......#.#.....#...#.#...#.#.#.............#.#...#.#...#...#...#.#.#.....#...#.#.....#.....#...#.#.#.....#...#.#...#...#...#.......#...#...#
+#######.#.#####.#.#.#.#####.#.#.###########.#.#####.###.###.#.#.#.#.#####.###.#.#####.#.###.#.###.#.#.#####.#.#.#.###.#############.#####.#.#
+#.......#.......#.#...###...#.#.#.........#.#.#.....#...#...#.#.#.#.#.....###.#.#.....#.###...###...#.......#...#...#.#.............#...#.#.#
+#.###############.#######.###.#.#.#######.#.#.#.#####.###.###.#.#.#.#.#######.#.#.#####.###########################.#.#.#############.#.#.#.#
+#.........#.......#.....#.....#...#.......#...#.....#...#.#...#.#.#.#.###...#...#.....#.#.......#...#...............#.#.#...#...#.....#...#.#
+#########.#.#######.###.###########.###############.###.#.#.###.#.#.#.###.#.#########.#.#.#####.#.#.#.###############.#.#.#.#.#.#.#########.#
+#.........#.#.....#...#.###...###...#...#...###...#.....#...#...#.#.#.....#...#.......#.#.#...#.#.#.#.....#...#.......#...#...#...#.........#
+#.#########.#.###.###.#.###.#.###.###.#.#.#.###.#.###########.###.#.#########.#.#######.#.#.#.#.#.#.#####.#.#.#.###################.#########
+#...#...#...#...#.....#.....#...#.....#...#.....#.........###...#.#.#...#.....#.........#...#.#.#.#.#...#...#...#...#.........#...#.....#...#
+###.#.#.#.#####.###############.#########################.#####.#.#.#.#.#.###################.#.#.#.#.#.#########.#.#.#######.#.#.#####.#.#.#
+###...#.#.#.....#...#.........#.......#...........#.....#.....#.#.#...#.#.###.........#...#...#...#...#.......#...#...###...#...#.....#...#.#
+#######.#.#.#####.#.#.#######.#######.#.#########.#.###.#####.#.#.#####.#.###.#######.#.#.#.#################.#.#########.#.#########.#####.#
+#...#...#.#.....#.#.#.#.....#...#...#...###...###.#...#.#...#.#.#.#.....#.#...#.....#...#.#...#...#...#...###.#...........#.......###.....#.#
+#.#.#.###.#####.#.#.#.#.###.###.#.#.#######.#.###.###.#.#.#.#.#.#.#.#####.#.###.###.#####.###.#.#.#.#.#.#.###.###################.#######.#.#
+#.#.#.....#.....#.#.#.#...#.....#.#.........#...#.....#...#...#...#...#...#...#.#...#...#.....#.#.#.#...#...#.#...#.....#...#...#.....###.#.#
+#.#.#######.#####.#.#.###.#######.#############.#####################.#.#####.#.#.###.#.#######.#.#.#######.#.#.#.#.###.#.#.#.#.#####.###.#.#
+#.#.#...###.....#.#...###...#.....#.....#...#...#...#...#...#.......#...###...#.#...#.#.#.......#.#.#.......#...#.#...#.#.#.#.#.......#...#.#
+#.#.#.#.#######.#.#########.#.#####.###.#.#.#.###.#.#.#.#.#.#.#####.#######.###.###.#.#.#.#######.#.#.###########.###.#.#.#.#.#########.###.#
+#.#.#.#.#...###...#...#...#...###...###...#.#.....#...#...#...#.....#...#...#...#...#.#.#.###...#...#...........#...#.#...#.#...#.....#.#...#
+#.#.#.#.#.#.#######.#.#.#.#######.#########.###################.#####.#.#.###.###.###.#.#.###.#.###############.###.#.#####.###.#.###.#.#.###
+#.#...#...#.#...#...#...#...#...#.......###...#...#...#.........#.....#.#...#.###.....#...#...#.................###...#...#...#...#...#...###
+#.#########.#.#.#.#########.#.#.#######.#####.#.#.#.#.#.#########.#####.###.#.#############.###########################.#.###.#####.#########
+#.........#.#.#...#.....#...#.#.###.....#...#...#.#.#.#...#.....#.....#...#...#...#...#...#.............................#...#.#...#...#...###
+#########.#.#.#####.###.#.###.#.###.#####.#.#####.#.#.###.#.###.#####.###.#####.#.#.#.#.#.#################################.#.#.#.###.#.#.###
+#.......#.#.#.#.....#...#.....#.....###...#...###...#.....#...#...###.#...###...#...#...#.....#.....#...#.......#.....#.....#.#.#...#...#...#
+#.#####.#.#.#.#.#####.#################.#####.###############.###.###.#.#####.###############.#.###.#.#.#.#####.#.###.#.#####.#.###.#######.#
+#...#...#.#.#...#.....#.....#...........#...#...###...###...#...#.#...#.....#...............#.#...#...#.#.....#...###.#.....#...###...#.....#
+###.#.###.#.#####.#####.###.#.###########.#.###.###.#.###.#.###.#.#.#######.###############.#.###.#####.#####.#######.#####.#########.#.#####
+#...#...#.#.#...#.#...#...#.#.#...........#...#.....#...#.#.#...#...#.......#...............#.....#...#.......#.....#.......#...#...#...#...#
+#.#####.#.#.#.#.#.#.#.###.#.#.#.#############.#########.#.#.#.#######.#######.#####################.#.#########.###.#########.#.#.#.#####.#.#
+#.....#...#...#.#...#...#.#.#.#.....#...#...#.#...#...#...#.#.......#.#.....#.................#.....#.#...###...#...#...###...#...#.......#.#
+#####.#########.#######.#.#.#.#####.#.#.#.#.#.#.#.#.#.#####.#######.#.#.###.#################.#.#####.#.#.###.###.###.#.###.###############.#
+#...#.........#.#...###...#...#...#...#.#.#.#...#...#.#.....#.......#...#...#.....#...#.......#...#...#.#...#.#...###.#...#.#...............#
+#.#.#########.#.#.#.###########.#.#####.#.#.#########.#.#####.###########.###.###.#.#.#.#########.#.###.###.#.#.#####.###.#.#.###############
+#.#...........#...#.#...###...#.#.....#...#...###...#.#.....#.....#.....#.###...#...#.#.#...#.....#...#.#...#.#.#...#.#...#.#.......###...###
+#.#################.#.#.###.#.#.#####.#######.###.#.#.#####.#####.#.###.#.#####.#####.#.#.#.#.#######.#.#.###.#.#.#.#.#.###.#######.###.#.###
+#...#...#...#.....#...#.#...#.#.....#.......#...#.#.#.......###...#...#...#.....#...#.#...#...###...#...#.#...#...#...#.....#.....#.....#...#
+###.#.#.#.#.#.###.#####.#.###.#####.#######.###.#.#.###########.#####.#####.#####.#.#.###########.#.#####.#.#################.###.#########.#
+###...#...#...###.#...#.#...#.....#.......#...#.#.#...#.....#...#.....#...#.......#.#.#.......#...#.......#.#.........#...#...###...........#
+#################.#.#.#.###.#####.#######.###.#.#.###.#.###.#.###.#####.#.#########.#.#.#####.#.###########.#.#######.#.#.#.#################
+#.................#.#.#...#.....#.........#...#...#...#.#...#...#.#...#.#...#...#...#...#.....#.............#.......#...#.#...#...#...#...###
+#.#################.#.###.#####.###########.#######.###.#.#####.#.#.#.#.###.#.#.#.#######.#########################.#####.###.#.#.#.#.#.#.###
+#...................#...#.#...#...........#.....#...#...#...###.#.#.#.#...#.#.#.#.......#...#...#...#.......#.......#...#.....#.#...#...#...#
+#######################.#.#.#.###########.#####.#.###.#####.###.#.#.#.###.#.#.#.#######.###.#.#.#.#.#.#####.#.#######.#.#######.###########.#
+#...###.................#...#.............#.....#.....#.....#...#...#...#.#.#.#.###...#...#.#.#...#...#...#...#...###.#.#.....#.#.......#...#
+#.#.###.###################################.###########.#####.#########.#.#.#.#.###.#.###.#.#.#########.#.#####.#.###.#.#.###.#.#.#####.#.###
+#.#.....#.........#...#.....#...........###.............#...#.......#...#.#.#.#.#...#...#.#.#.#.......#.#.....#.#...#.#.#...#...#.....#.#...#
+#.#######.#######.#.#.#.###.#.#########.#################.#.#######.#.###.#.#.#.#.#####.#.#.#.#.#####.#.#####.#.###.#.#.###.#########.#.###.#
+#.........#.......#.#.#.#...#.#.........#.....#...###.....#.#######.#...#.#.#.#.#.....#.#.#.#...#...#.#.#...#...#...#.#.###.#.........#...#.#
+###########.#######.#.#.#.###.#.#########.###.#.#.###.#####.#######.###.#.#.#.#.#####.#.#.#.#####.#.#.#.#.#.#####.###.#.###.#.###########.#.#
+#...###.....#...#...#...#.....#.....#...#.#...#.#...#...#...#####...#...#.#.#.#.#.....#...#.....#.#.#.#.#.#.......###.#.#...#.....#.....#...#
+#.#.###.#####.#.#.#################.#.#.#.#.###.###.###.#.#######.###.###.#.#.#.#.#############.#.#.#.#.#.###########.#.#.#######.#.###.#####
+#.#.#...#...#.#.#.#.............###...#...#...#...#...#.#...#####..S#...#.#...#.#.#.......#.....#.#.#...#...#.........#...#...#...#.#...#...#
+#.#.#.###.#.#.#.#.#.###########.#############.###.###.#.###.###########.#.#####.#.#.#####.#.#####.#.#######.#.#############.#.#.###.#.###.#.#
+#.#...#...#...#...#...........#.#.............###...#.#.#...#########...#.....#.#...#...#.#.###...#...#.....#.#.....#.....#.#.#.....#.....#.#
+#.#####.#####################.#.#.#################.#.#.#.###########.#######.#.#####.#.#.#.###.#####.#.#####.#.###.#.###.#.#.#############.#
+#...#...#.....................#.#...#.....#.....#...#.#.#...#########.#...#...#.....#.#.#.#...#.....#.#.......#...#...###...#...............#
+###.#.###.#####################.###.#.###.#.###.#.###.#.###.#########.#.#.#.#######.#.#.#.###.#####.#.###########.###########################
+#...#.###...........#...#.....#.....#.#...#.#...#.#...#.#...#########.#.#.#.....#...#.#.#.#...#...#.#.###...#...#.....#...#.................#
+#.###.#############.#.#.#.###.#######.#.###.#.###.#.###.#.###########.#.#.#####.#.###.#.#.#.###.#.#.#.###.#.#.#.#####.#.#.#.###############.#
+#...#...#.......###...#...#...#.....#.#...#.#...#.#.#...#.###########.#.#.....#.#...#.#.#.#.#...#.#.#...#.#.#.#.#...#...#...#.....#...#.....#
+###.###.#.#####.###########.###.###.#.###.#.###.#.#.#.###.###########.#.#####.#.###.#.#.#.#.#.###.#.###.#.#.#.#.#.#.#########.###.#.#.#.#####
+###.....#.....#.#.......###.#...#...#.#...#...#...#.#.#...#########...#.#.....#...#.#.#.#.#.#...#...###.#.#.#.#.#.#...#.......#...#.#...#...#
+#############.#.#.#####.###.#.###.###.#.#####.#####.#.#.###########.###.#.#######.#.#.#.#.#.###.#######.#.#.#.#.#.###.#.#######.###.#####.#.#
+#.........#...#...#...#.....#...#.....#.#.....###...#.#...#########.....#.#...#...#...#.#.#...#...#.....#.#...#...#...#.....###...#.......#.#
+#.#######.#.#######.#.#########.#######.#.#######.###.###.###############.#.#.#.#######.#.###.###.#.#####.#########.#######.#####.#########.#
+#.......#.#...#.....#.....#.....#.......#.......#...#.#...###########.....#.#.#.#.......#...#...#.#.....#.........#...#...#.....#.#.....#...#
+#######.#.###.#.#########.#.#####.#############.###.#.#.#############.#####.#.#.#.#########.###.#.#####.#########.###.#.#.#####.#.#.###.#.###
+###.....#.....#.#.........#.#.....#.....#.......###.#.#...###########.....#.#...#.#...#...#...#...#.....#.........#...#.#.#.....#.#.###.#...#
+###.###########.#.#########.#.#####.###.#.#########.#.###.###############.#.#####.#.#.#.#.###.#####.#####.#########.###.#.#.#####.#.###.###.#
+#...#.....#...#.#...#...#...#.....#.###.#.###.....#...###.###.....#.......#...#...#.#.#.#.#...#...#.....#...#...#...#...#.#.....#.#...#.#...#
+#.###.###.#.#.#.###.#.#.#.#######.#.###.#.###.###.#######.###.###.#.#########.#.###.#.#.#.#.###.#.#####.###.#.#.#.###.###.#####.#.###.#.#.###
+#...#...#...#...###...#.#.###.....#.#...#...#...#...#...#.#E#.#...#...#...#...#...#.#...#.#.#...#.......#...#.#.#.#...###.#...#.#.#...#...###
+###.###.###############.#.###.#####.#.#####.###.###.#.#.#.#.#.#.#####.#.#.#.#####.#.#####.#.#.###########.###.#.#.#.#####.#.#.#.#.#.#########
+###.....#...#...###...#.#.#...#...#.#.#...#.....#...#.#...#...#.#...#...#.#.#.....#.#.....#.#.......#...#.....#.#.#.....#...#...#.#.........#
+#########.#.#.#.###.#.#.#.#.###.#.#.#.#.#.#######.###.#########.#.#.#####.#.#.#####.#.#####.#######.#.#.#######.#.#####.#########.#########.#
+###.......#...#.....#...#.#...#.#.#.#...#.#.....#.###.....#...#...#...###...#.....#.#.#...#.#.......#.#...#.....#.#.....#.......#.#...#.....#
+###.#####################.###.#.#.#.#####.#.###.#.#######.#.#.#######.###########.#.#.#.#.#.#.#######.###.#.#####.#.#####.#####.#.#.#.#.#####
+#...#.......#...#.....#...#...#.#...###...#...#...#.......#.#...#...#...........#...#...#.#.#.#...#...#...#.....#.#.......#...#.#.#.#.#.#...#
+#.###.#####.#.#.#.###.#.###.###.#######.#####.#####.#######.###.#.#.###########.#########.#.#.#.#.#.###.#######.#.#########.#.#.#.#.#.#.#.#.#
+#...#.#...#.#.#...###.#.#...#...#.......#...#.....#.....#...#...#.#.#...#...#...###...#...#.#.#.#.#.###.#...#...#.......#...#.#.#...#.#...#.#
+###.#.#.#.#.#.#######.#.#.###.###.#######.#.#####.#####.#.###.###.#.#.#.#.#.#.#####.#.#.###.#.#.#.#.###.#.#.#.#########.#.###.#.#####.#####.#
+#...#.#.#...#.###.....#.#.....#...#.....#.#.#.....#.....#.###.....#.#.#...#...#.....#...#...#.#.#.#...#...#.#.......###...###...#.....#...#.#
+#.###.#.#####.###.#####.#######.###.###.#.#.#.#####.#####.#########.#.#########.#########.###.#.#.###.#####.#######.#############.#####.#.#.#
+#...#.#...#...#...#.....###.....#...#...#.#.#.....#.#...#.........#.#...###...#.......#...#...#.#...#.#.....#...#...#.......#...#...#...#...#
+###.#.###.#.###.###.#######.#####.###.###.#.#####.#.#.#.#########.#.###.###.#.#######.#.###.###.###.#.#.#####.#.#.###.#####.#.#.###.#.#######
+#...#...#.#.#...#...#.......#...#...#.....#...#...#.#.#...#.....#.#...#...#.#...#.....#...#.#...###...#...#...#.#.....#...#...#...#.#.###...#
+#.#####.#.#.#.###.###.#######.#.###.#########.#.###.#.###.#.###.#.###.###.#.###.#.#######.#.#.###########.#.###.#######.#.#######.#.#.###.#.#
+#...#...#.#.#...#...#.....#...#.#...###...###.#...#.#.#...#.###.#...#...#...#...#.#.....#.#...###.........#...#...#.....#.....#...#.#.....#.#
+###.#.###.#.###.###.#####.#.###.#.#####.#.###.###.#.#.#.###.###.###.###.#####.###.#.###.#.#######.###########.###.#.#########.#.###.#######.#
+#...#...#.#.#...#...#.....#.###.#.#.....#.....#...#.#.#...#...#...#.#...#...#.###...###.#...#...#.......#.....#...#.........#.#...#...#...#.#
+#.#####.#.#.#.###.###.#####.###.#.#.###########.###.#.###.###.###.#.#.###.#.#.#########.###.#.#.#######.#.#####.###########.#.###.###.#.#.#.#
+#.#...#.#.#.#...#.#...#...#.#...#.#.#...#...#...#...#...#...#...#.#.#...#.#.#.........#.#...#.#.........#.....#...#...#...#.#.#...#...#.#.#.#
+#.#.#.#.#.#.###.#.#.###.#.#.#.###.#.#.#.#.#.#.###.#####.###.###.#.#.###.#.#.#########.#.#.###.###############.###.#.#.#.#.#.#.#.###.###.#.#.#
+#...#...#...###...#.....#...#.....#...#...#...###.......###.....#...###...#...........#...###.................###...#...#...#...###.....#...#
+#############################################################################################################################################

20/main.rb

@@ -0,0 +1,118 @@
+#!/usr/bin/env ruby
+
+require "debug"
+
+input = (ARGV.first.nil? ? DATA : ARGF)
+  .readlines(chomp: true)
+  .map(&:chars)
+
+class PriorityQueue < Array
+  alias_method :extract_min, :shift
+
+  def <<(v)
+    super
+    sort_by!(&:last)
+  end
+end
+
+def unbounded?(graph, node)
+  node.first < 0 ||
+    node.last < 0 ||
+    node.first >= graph.size ||
+    node.last >= graph.first.size
+end
+
+def dijkstra(graph, source, target)
+  queue = PriorityQueue.new
+  dist = Hash.new
+  prev = Hash.new
+
+  queue << [source, 0]
+  dist[source] = 0
+  prev[source] = nil
+
+  until queue.empty?
+    node, picoseconds = queue.extract_min
+
+    [[0, 1], [0, -1], [1, 0], [-1, 0]]
+      .map { |dx, dy| [node.first + dx, node.last + dy] }
+      .reject { unbounded?(graph, _1) }
+      .each do |neighbor|
+        next if graph.dig(*neighbor) == "#"
+
+        if dist[neighbor].nil? || picoseconds + 1 < dist[neighbor]
+          dist[neighbor] = picoseconds + 1
+          prev[neighbor] = node
+          queue << [neighbor, picoseconds + 1]
+        end
+      end
+  end
+
+  path = Array.new
+  u = target
+  while prev[u]
+    path.unshift(u)
+    u = prev[u]
+  end
+
+  return dist, prev, path
+end
+
+def find_cheats(graph, dist, path, finish)
+  cheats = Hash.new
+  path.each do |node|
+    [[0, 2], [0, -2], [2, 0], [-2, 0]]
+      .map { |dx, dy| [node.first + dx, node.last + dy] }
+      .reject { unbounded?(graph, _1) }
+      .each do |neighbor|
+        next if graph.dig(*neighbor) == "#"
+
+        next if dist[node] >= dist[neighbor]
+
+        cheats[[node, neighbor]] = dist[neighbor] - dist[node] - 2
+      end
+  end
+
+  return cheats
+end
+
+def manhattan_distance(node1, node2)
+  (node1.first - node2.first).abs + (node1.last - node2.last).abs
+end
+
+def discover(char, graph)
+  (0...graph.size).each do |x|
+    (0...graph.first.size).each do |y|
+      return [x, y] if char == graph.dig(x, y)
+    end
+  end
+end
+
+start = discover("S", input)
+finish = discover("E", input)
+
+dist, prev, path = dijkstra(input, start, finish)
+
+p find_cheats(input, dist, [start] + path, finish)
+  .values.tally.select { _1 >= 100 }.values.sum
+
+p dist.keys.combination(2)
+  .select { manhattan_distance(_1, _2) <= 20 }
+  .count { dist[_2] - dist[_1] >= manhattan_distance(_1, _2) + 100 }
+
+__END__
+###############
+#...#...#.....#
+#.#.#.#.#.###.#
+#S#...#.#.#...#
+#######.#.#.###
+#######.#.#...#
+#######.#.###.#
+###..E#...#...#
+###.#######.###
+#...###...#...#
+#.#####.#.###.#
+#.#...#.#.#...#
+#.#.#.#.#.#.###
+#...#...#...###
+###############