This question isn’t about integers “given no assumptions”. It’s about the int primitive in Java.
lsusr
Karma: 726
If you happen to know the answer already then the question is ruined. In this way, every algorithm puzzle in the world can be ruined by trivia. For an algorithm question to be interesting, I hope the reader doesn’t already know the answer and has to figure it out her/himself. So in questions #1 and #3, I’m hoping the reader doesn’t know the relevant trivia and will instead independently derive the answers without looking them up.
I’m not trying to ask “Do you know how Poland cracked the Enigma?” I’m trying to ask “Can you figure out how Poland cracked the Enigma?”
I don’t grade these questions. These questions are for fun and self-improvement. Though I could imagine a timed written test with dozens of questions like this where the testee gets one point for each correct answer and loses one point for each incorrect answer. A sufficiently large number of questions might help counteract the individual variance.
There is no such algorithm.
Fixed typo.
Let’s imagine the daily code the machine is set it with is AAA. Would this turn the plaintext “X” into the ‘ciphertext’ “X”?
No, for a couple reasons.
First of all, each of the rotors have a different wiring. For example, in the first rotor, A might be wired to B and B might be wired to M.
Secondly, the reflector makes it impossible for any letter to be mapped to itself.
You are correct that the plaintext AAA is unlikely to be encrypted into the same letter multiple times such as BBB, due to the rotating rotors.
3 Interview-like Algorithm Questions for Programmers
I can read Chinese.
The two most important things to understand about startup investing, as a business, are (1) that effectively all the returns are concentrated in a few big winners, and (2) that the best ideas look initially like bad ideas. ― Black Swan Farming by Paul Graham
I’ve known many people like you describe. One was an MBA who earns at least a quarter of a million dollars per year as a manager at a major tech company. Another is a former CEO. A third wrote software for a quantitative training firm. They all tried to start startups. They said lots of incorrect things to me. For example, the MBA once lectured me about how The Art of War is irrelevant to the study of business strategy.
Nothing I said ever convinced these confident people they were wrong. I quietly started my own startup. One after another, all of their businesses failed, often after wasting lots of money. Meanwhile, my startup chugs along.
Most of them learned their lesson and quit the startup game. Except the most capable one, who learned a different lesson and joined my startup as a co-founder.
Importing masks from China
We started shipping the earliest orders yesterday. If an order is placed today, we expect to ship on April 6, 2020.
We expect to have more in about a month.
This is a great idea. I should add an article on the subject to this series.
That’s a good question. Here’s our official answer from the FAQ:
You don’t need two bands, but having bands on each hand increases the efficacy of alerting you whenever you touch your face. Putting one band on your dominant hand will alert when that one hand touches your face, which is more effective than no alerting.
In my experience using our similar product for nail biting, one bracelet is more than half as effective than two bracelets. There are two reasons for this. The first is that putting a bracelet on my dominant hand catches more than half of face touches. But more importantly, the device is designed around the idea of awareness. In my personal experience, awareness of nail biting with my right hand generalizes (substantially, though not completely) to my left hand.
I hope so too! Stay sanitary!
What I’m doing to fight Coronavirus
Seattle’s Century Ballroom has cancelled all of its classes and dances since last Friday.
I am not a doctor. Instead, here is advice from the WHO.
Wash your hands frequently
Maintain social distancing
Avoid touching eyes, nose and mouth [emphasis mine]
Practice respiratory hygiene
If you have fever, cough and difficulty breathing, seek medical care early
Stay informed and follow advice given by your healthcare provider
Their first recommendation is to wash your hands. Wash long with lots of scrubbing for 20-30 seconds. Scrubbing your hands under running water may be more important than soap[1]. (Use soap anyway!)
If you are washing your hands frequently and maintaining social distancing to the extent you can, then you should pay attention to not touching your face. We all touch our faces unconsciously. It’s easier to do something consciously (like wear goggles) than to not do something unconsciously (like repeatedly choosing to not touch your face).
I would bet many points on Metaculus that if goggles are in place over your eyes then you are less likely to touch your eyes with your hands.
By the way, here are the WHO guidelines for how to use a mask properly.
These details about hand-washing come from recent episodes of This Week in Virology, a podcast about virology by virologists. ↩︎
4 Kinds of Learning
Much appreciated. Thank you for fixing this in a timely manner.
Yes. They move independent of which character it is.