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+--- Day 7: Recursive Circus ---
+
+Wandering further through the circuits of the computer, you come upon
+a tower of programs that have gotten themselves into a bit of trouble.
+A recursive algorithm has gotten out of hand, and now they're balanced
+precariously in a large tower.
+
+One program at the bottom supports the entire tower. It's holding a
+large disc, and on the disc are balanced several more sub-towers. At
+the bottom of these sub-towers, standing on the bottom disc, are other
+programs, each holding their own disc, and so on. At the very tops of
+these sub-sub-sub-...-towers, many programs stand simply keeping the
+disc below them balanced but with no disc of their own.
+
+You offer to help, but first you need to understand the structure of
+these towers. You ask each program to yell out their name, their
+weight, and (if they're holding a disc) the names of the programs
+immediately above them balancing on that disc. You write this
+information down (your puzzle input). Unfortunately, in their panic,
+they don't do this in an orderly fashion; by the time you're done,
+you're not sure which program gave which information.
+
+For example, if your list is the following:
+
+pbga (66)
+xhth (57)
+ebii (61)
+havc (66)
+ktlj (57)
+fwft (72) -> ktlj, cntj, xhth
+qoyq (66)
+padx (45) -> pbga, havc, qoyq
+tknk (41) -> ugml, padx, fwft
+jptl (61)
+ugml (68) -> gyxo, ebii, jptl
+gyxo (61)
+cntj (57)
+
+...then you would be able to recreate the structure of the towers that
+looks like this:
+
+                gyxo
+              /     
+         ugml - ebii
+       /      \     
+      |         jptl
+      |        
+      |         pbga
+     /        /
+tknk --- padx - havc
+     \        \
+      |         qoyq
+      |             
+      |         ktlj
+       \      /     
+         fwft - cntj
+              \     
+                xhth
+
+In this example, tknk is at the bottom of the tower (the bottom
+program), and is holding up ugml, padx, and fwft. Those programs are,
+in turn, holding up other programs; in this example, none of those
+programs are holding up any other programs, and are all the tops of
+their own towers. (The actual tower balancing in front of you is much
+larger.)
+
+Before you're ready to help them, you need to make sure your
+information is correct. What is the name of the bottom program?
+
+Your puzzle answer was xegshds.
+
+--- Part Two ---
+
+The programs explain the situation: they can't get down. Rather, they
+could get down, if they weren't expending all of their energy trying
+to keep the tower balanced. Apparently, one program has the wrong
+weight, and until it's fixed, they're stuck here.
+
+For any program holding a disc, each program standing on that disc
+forms a sub-tower. Each of those sub-towers are supposed to be the
+same weight, or the disc itself isn't balanced. The weight of a tower
+is the sum of the weights of the programs in that tower.
+
+In the example above, this means that for ugml's disc to be balanced,
+gyxo, ebii, and jptl must all have the same weight, and they do: 61.
+
+However, for tknk to be balanced, each of the programs standing on its
+disc and all programs above it must each match. This means that the
+following sums must all be the same:
+
+    ugml + (gyxo + ebii + jptl) = 68 + (61 + 61 + 61) = 251
+    padx + (pbga + havc + qoyq) = 45 + (66 + 66 + 66) = 243
+    fwft + (ktlj + cntj + xhth) = 72 + (57 + 57 + 57) = 243
+
+As you can see, tknk's disc is unbalanced: ugml's stack is heavier
+than the other two. Even though the nodes above ugml are balanced,
+ugml itself is too heavy: it needs to be 8 units lighter for its stack
+to weigh 243 and keep the towers balanced. If this change were made,
+its weight would be 60.
+
+Given that exactly one program is the wrong weight, what would its
+weight need to be to balance the entire tower?
+
+Your puzzle answer was 299.
+
+Both parts of this puzzle are complete! They provide two gold stars: **