# Solution to EAsT camPUS

#### by Anderson Wang, Ben Yang, Cami Ramirez-Arau, Azalea Weisblat and Lewis Chen

We are presented with a binary tree where some nodes have letters. When going up the tree, all the edges to the left are brown, and all edges to the right are black.

Reading all the letters from left to right (or, equivalently, doing an in-order tree traversal) gives the message BE QUICK DO THIS GO SEE THE WEST PARALLEL CHECK OUT ITS NORTHERNMOST SECTION READ NAME GOOD JOB GO OFF BACK TO ANSWERS. MIT's East Campus dormitory consists of two parallels, west and east, and the northernmost section of the west parallel is called “Wood” (this can be seen on Google Maps or by going there in person).

The “WOOD” message, combined with the weird capitalization in the East Campus logo (which spells out “EAT PUS” and “scam”) hints at the main aha: each answer can be unwoven into two words, one of which is an object made of wood. For example, BITE MARK can be split into BARK and ITEM.

Now that we have split the answers, we can return to the tree. Going left along the tree where the next letter of the word is wooden (along a brown edge), and going right where the next letter is not wooden (along a black edge), we find that each answer passes through exactly three letters. The paths and letters are listed below:

Answer Wood word Other word L/R sequence (L=wood, R=non-wood) Result of following the L/R sequence in the tree
BITE MARK BARK ITEM L R R R R L L L _ _ _ K I _ U _
BOAT RIDE BOARD TIE L L L R L R L R _ _ B _ Q _ D _
CALANTHE LATH CANE R R L L R L L R _ _ G R _ _ _ N
LA DODGERS LOG ADDERS L R R L R L R R R _ _ _ E _ _ P L _
POUND STERLING POST UNDERLING L L R R R L L R R R R R R _ _ H O _ _ S _ _ _ _ _ _
SEA BREAM BEAM SEAR R R R L R L L L _ _ _ J A _ _ F
STOWING TWIG SON R L R L L R L _ _ T _ _ C M

(The L=wood, R=non-wood correspondence is meant to be clued by the coloring, but it's easily verified — if R and L are switched, most of the paths cannot be drawn on the tree.)

When we've done this for enough of the answers, we notice that the letters are all unique and go from A to U, using each of those 21 letters once. We can take the letter of the answer corresponding to the A extracted from the tree, then the letter corresponding to the B, and so on (for example, A corresponds to the 5th letter in SEA BREAM, which is R):

Letter in tree Corresponding letter in answer
A R
B A
C N
D D
E O
F M
G L
H U
I M
J B
K E
L R
M G
N E
O N
P E
Q R
R A
S T
T O
U R

East Campus needs a RANDOM LUMBER GENERATOR to keep its fire burning!

## Authors’ Notes

This puzzle went through many many iterations before settling on this version. Early versions used the numbers 1–21 instead of letters A–U (and no extraneous numbers), but this made the 7 paths very obvious, and one testsolving group managed to solve the meta by brute-forcing all 7! matchings of answers to paths. Another issue was that solvers mainly focused on analyzing the tree instead of looking for the commonality between the answers. We tried to rectify this by making an interactive game instead of an image, the intent being to discourage searching through the tree before understanding where to go, but our testers brute-forced their way through the tree to find all the numbers anyways.

Eventually we decided that including extraneous numbers would be the best way of addressing this issue, but it felt inelegant to have numbers that weren't used for anything. This finally led to using letters instead of numbers, which let us add an additional cluephrase that also told solvers to look at the answers. The cluephrase did need to include 21 specific letters in relative positions, which is why it had things like BE QUICK and GOOD JOB.

Additionally, the original version of this puzzle used tree names instead of things made of wood (we really liked SCHOLARLY = HOLLY + SCAR), but at some point we noticed that it was somewhat similar to the Arbor Day/Valentine's Day meta from the 2019 MH. As a result, it was changed to words that could go before WOOD, like DEAD or SANDAL, but this aha proved too difficult in testsolving, so we finally settled on this version.

The tree presentation of this puzzle was originally intended to look like a fire, but in styling the interactive HTML version of it (since reading letters from the enormous-image version was a huge pain) we found it much easier to make something that looked like a tree than a fire.