Reorder days into src

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+--- Part Two ---
+
+You arrive at the vault only to discover that there is not one vault, but four - each with its own
+entrance.
+
+On your map, find the area in the middle that looks like this:
+
+...
+.@.
+...
+
+Update your map to instead use the correct data:
+
+@#@
+###
+@#@
+
+This change will split your map into four separate sections, each with its own entrance:
+
+#######       #######
+#a.#Cd#       #a.#Cd#
+##...##       ##@#@##
+##.@.##  -->  #######
+##...##       ##@#@##
+#cB#Ab#       #cB#Ab#
+#######       #######
+
+Because some of the keys are for doors in other vaults, it would take much too long to collect all
+of the keys by yourself.  Instead, you deploy four remote-controlled robots. Each starts at one of
+the entrances (@).
+
+Your goal is still to collect all of the keys in the fewest steps, but now, each robot has its own
+position and can move independently.  You can only remotely control a single robot at a time.
+Collecting a key instantly unlocks any corresponding doors, regardless of the vault in which the key
+or door is found.
+
+For example, in the map above, the top-left robot first collects key a, unlocking door A in the
+bottom-right vault:
+
+#######
+#@.#Cd#
+##.#@##
+#######
+##@#@##
+#cB#.b#
+#######
+
+Then, the bottom-right robot collects key b, unlocking door B in the bottom-left vault:
+
+#######
+#@.#Cd#
+##.#@##
+#######
+##@#.##
+#c.#.@#
+#######
+
+Then, the bottom-left robot collects key c:
+
+#######
+#@.#.d#
+##.#@##
+#######
+##.#.##
+#@.#.@#
+#######
+
+Finally, the top-right robot collects key d:
+
+#######
+#@.#.@#
+##.#.##
+#######
+##.#.##
+#@.#.@#
+#######
+
+In this example, it only took 8 steps to collect all of the keys.
+
+Sometimes, multiple robots might have keys available, or a robot might have to wait for multiple
+keys to be collected:
+
+###############
+#d.ABC.#.....a#
+######@#@######
+###############
+######@#@######
+#b.....#.....c#
+###############
+
+First, the top-right, bottom-left, and bottom-right robots take turns collecting keys a, b, and c, a
+total of 6 + 6 + 6 = 18 steps. Then, the top-left robot can access key d, spending another 6 steps;
+collecting all of the keys here takes a minimum of 24 steps.
+
+Here's a more complex example:
+
+#############
+#DcBa.#.GhKl#
+#.###@#@#I###
+#e#d#####j#k#
+###C#@#@###J#
+#fEbA.#.FgHi#
+#############
+
+
+ - Top-left robot collects key a.
+
+ - Bottom-left robot collects key b.
+
+ - Top-left robot collects key c.
+
+ - Bottom-left robot collects key d.
+
+ - Top-left robot collects key e.
+
+ - Bottom-left robot collects key f.
+
+ - Bottom-right robot collects key g.
+
+ - Top-right robot collects key h.
+
+ - Bottom-right robot collects key i.
+
+ - Top-right robot collects key j.
+
+ - Bottom-right robot collects key k.
+
+ - Top-right robot collects key l.
+
+
+In the above example, the fewest steps to collect all of the keys is 32.
+
+Here's an example with more choices:
+
+#############
+#g#f.D#..h#l#
+#F###e#E###.#
+#dCba@#@BcIJ#
+#############
+#nK.L@#@G...#
+#M###N#H###.#
+#o#m..#i#jk.#
+#############
+
+One solution with the fewest steps is:
+
+
+ - Top-left robot collects key e.
+
+ - Top-right robot collects key h.
+
+ - Bottom-right robot collects key i.
+
+ - Top-left robot collects key a.
+
+ - Top-left robot collects key b.
+
+ - Top-right robot collects key c.
+
+ - Top-left robot collects key d.
+
+ - Top-left robot collects key f.
+
+ - Top-left robot collects key g.
+
+ - Bottom-right robot collects key k.
+
+ - Bottom-right robot collects key j.
+
+ - Top-right robot collects key l.
+
+ - Bottom-left robot collects key n.
+
+ - Bottom-left robot collects key m.
+
+ - Bottom-left robot collects key o.
+
+
+This example requires at least 72 steps to collect all keys.
+
+After updating your map and using the remote-controlled robots, what is the fewest steps necessary
+to collect all of the keys?
+
+