Ask HN: What's the most creative 'useless' program you've ever written?

So if the probability of finding a mine at any given spot is given by p, then the probability of finding a mine in the top left during gameplay for cases where one does not click it first (in which case it is 0?) is 1 for the case where you clicked on a mine first with probability p, and then p for the remainder.

So the total probability p' is p * 1 + (1 - p) * p, or 2p - p^2.

Wikipedia says

> Beginner is usually on an 8x8 or 9x9 board containing 10 mines, Intermediate is usually on a 16x16 board with 40 mines and expert is usually on a 30x16 board with 99 mines; however, there is usually an option to customise board size and mine count.

  8x8   10 mines  p = 0.16 p' = 0.29 ratio = 1.84
  9x9   10 mines  p = 0.12 p' = 0.23 ratio = 1.88
  16x16 40 mines  p = 0.16 p' = 0.29 ratio = 1.84
  30x16 99 mines  p = 0.21 p' = 0.37 ratio = 1.79

It’s a window into the small web. Just click a button to open a random site harvested from are.na, marginalia, etc. It used to just be a server but ever since I’ve made this TikTok-esque UX I’ve been kinda addicted to it

1. A Chrome extension that slowly rotated every on the page (think 1 degree every 10 minutes). Would be hard to notice unless a page had been left open for a while. 2. Another Chrome extension that would redirect to a full-screen gif of John Cena that would only load after a random number of page loads. 3. A horn sound that would play after every successful git commit, regardless of computer volume. 4. A Slack bot that would scrape another coworker's insufferable Reddit comments, store them in a database, and then use ML to interject the comments into our conversations based on some basic NLP. This one was my favorite.

I came across the St. Petersburg Paradox[1] recently. The gist of this is that there's a coin-flipping game where if you go by the mathematical laws of probability, the expected payout is infinite. Meaning, you should play the game if offered the chance to play it for any finite amount of money. And yet most people will instinctively look at this and say "I wouldn't buy in to this game for more than $SOME_SMALL_AMOUNT".

To help myself understand the dichotomy, I wrote a simulation of the game in Java, and ran through 1 million rounds of playing the game, randomizing the coin flips, determining the payout, and then calculating the average.

What I found was that I wouldn't buy into this game for more than a few dollars. Because the infinite payout can only happen with infinite coin tosses as far as I can see, which would require infinite time, making that outcome irrelevant in the real world. And in a million game experiment, the average payout was usually around $20, with that outcome being highly affected by outlier outcomes. The usual outcome of individual trials was generally around $2 to $4 or so.

Useful for anything? No, but it was something fun to play around with.

[1]: http://en.wikipedia.org/wiki/St._Petersburg_paradox

It seems to be because I named the function that displays output print(). But it should shadow window.print(), and in most browsers it does, so I don't know what's going on!

(At any rate, this is a web archive snapshot from 2020 so I can't update the code!)

Could you try a different browser? It's not much, but it might make you smile :)