Solution to Green Building
Answer: CLEAR ALL VINES
by Nathan Pinsker and Brian Chen
LIZ CLAIBORNE VIEWTIFUL JOE ESCAPE VELOCITY CAPTAIN HOOK ELECTRIC LIGHT ALL-SEEING LUMINESCENT LJUBLJANA ROMEO AND JULIET INTELLIGENCE STATE LINE ARMIN ZOGGELER NONCONFORMIST
This is the metapuzzle for the Green Building. We’re presented with a 13×5 grid of windows, with trees on either side of the bottom row. Furthermore, solving a puzzle in the round unlocks a switch corresponding to the next highest floor.
The switch can be toggled on and off, and turning it on lights up some windows on the building itself. If we decode the bottom row as five bit binary in order of the floors we spell FAMOUS MIT HACK.
One of the most famous Green Building hacks involved turning the building into a playable tetris game by lighting up the windows on the building’s northern face. A natural thing to do then would be to interpret our lighted-up grid as a Tetris grid.
Every meta answer contains some of the letters I, L, J, S, O, Z, T, corresponding to the seven possible Tetris pieces. By removing all the other letters, we can turn each answer into a sequence of tetris pieces. For each lighted-up board, we can identify an answer whose sequence of Tetris pieces clears the board when the pieces are dropped at the appropriate positions.
For example, the following board, corresponding to switch #1, is cleared with CAPTAIN HOOK. Removing all non-Tetris letters gives the sequence TIOO.
Each board can be uniquely cleared with a sequence of Tetris pieces obtained from an answer. Matching the answers to the boards is a little tricky, but there are a few heuristics we can use to make things easier. For example, the board corresponding to switch #1 initially has 9 lit squares. Since each Tetris line clear unlights five squares, this board must be cleared by a number of squares congruent to 1 modulo 5, which can only be achieved by tetromino sequences of length 4 or 9.
The full matchup is:
|Switch #||Answer||Piece Sequence|
|Switch 1||CAPTAIN HOOK||TIOO|
|Switch 3||ESCAPE VELOCITY||SLOIT|
|Switch 4||ARMIN ZOGGELER||IZOL|
|Switch 5||ROMEO AND JULIET||OOJLIT|
|Switch 8||LIZ CLAIBORNE||LIZLIO|
|Switch 9||VIEWTIFUL JOE||ITILJO|
|Switch 12||ELECTRICAL EQUIPMENT||LTILIT|
|Switch 13||STATE LINE||STTLI|
To finish, we simply re-order the first letters of the answers by the order of the switches they match up to to extract the answer: CLEAR ALL VINES.