Tech companies try to keep interview questions secret, preventing job candidates from preparing answers in advance. Applicants are taking back the power by publicly sharing their interview experiences on websites like Glassdoor and CareerCup. As a result, what was intended as a forum to help career aspirants navigate the job market has become more like WikiLeaks for puzzle lovers. This week, I declassify the Bezos documents, delivered straight to your browser window, free shipping of course.
According to a CareerCup post, the first puzzle comes from a software engineering interview: It’s based on a great premise of labeling blank dice faces to achieve a specific goal, but in case you solve it too quickly, they’ve added two bonus puzzles that also explore blank dice.
Missed last week’s puzzle? Check it out now! hereyou’ll find the answers at the bottom of today’s article. If you haven’t done last week’s questions yet, be careful not to read too far ahead.
Puzzle #44: Blank Dice
Amazon interview question: When you roll two regular dice and add the results together, you get a number between 2 and 12. However, not all numbers are equally likely (for example, if you roll a snake eye, you only get 2, but 7 comes up quite often). Imagine you have one regular die and one blank die (a small cube with no numbers). Label a blank die with a subset of numbers 0, 1, 2, 3, 4, 5, 6 When both dice are rolled, the total sum is 1 to 12 The odds are the same. You must label all sides of the blank die. It’s okay to have duplicate numbers.
Bonus Question Blank Dice, courtesy of Dmitry Kamenetsky: You have two blank dice, A and B, so label each with a number from 1 to 12 once (with no duplicates). Then, when you roll the dice, there is a 50% chance that A will land on a higher number than B, and a 50% chance that B will land on a higher number than A.
label three These are blank dice (with no repeats) that use each number from 1 to 18 once. This ensures that when you roll the dice, you have an equal chance of hitting the highest value on each die.
These may seem like tedious trials and errors, but they all have fairly intuitive solutions. The last one was particularly satisfying, but we need to solve a smaller case first and work through it.
We’ll bring you the answers and new puzzles on Mondays. Do you know of a fun puzzle we should feature here? Send us a message with X Jack Murtagh or by email gizmodopuzzle@gmail.com
Solution to puzzle #43: Anarchic Tic-Tac-Toe
Last week Tic-tac-toe variationsThe first player can always force a win by doing the following: Thanks to Kari Roth for emailing me the perfect solution with diagrams. Kari writes:
The twist on this variation is that you’re not actually trying to play three in a row, but rather forcing your opponent to play two in a row with the third position open.
Great insight! Here’s how player 1 wins:
You start in the center. The symbol doesn’t matter, so let’s say you start with an X. You can’t put an X on an empty space because that would mean you’d have three in a row next turn. You need to put an O, and you only have two options: a corner cell or an edge cell (the board is symmetrical so it doesn’t matter which corner or edge it is).
If you select a corner cell, place an O in the opposite corner.
Now I am in a Zugzwang state, which means that all legal moves are against me. The best move for me would be to pass, but the rules require me to move. Regardless of which cell I choose and what symbol I put there, I open three rows of cards for you.
Instead, if you place an O on an edge in your first move, follow a similar strategy to place an O on the opposite edge.
Now, the only way to stop me from giving you the win on the next turn is to place an O in one of the remaining edge cells, again mirroring it and placing me in zugzwang.
All my moves are losses, so the first player can always force a win in anarchic tic-tac-toe by opening in the center and mimicking his opponent’s moves until he has a chance to win.
