12:23 AM
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How Shuffled is This Sequence? Given a sequence \$S\$ with length \$n\$ of exactly one each of whole numbers from \$1\$ to \$n\$, your task is to return a number \$\sigma\$ indicating how shuffled it is. The shuffledness algorithm Total a 'shuffledness' value for each element \$\sigma_i\$ in s...

1:04 AM
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Is this board Latin-style? code-golf decision-problem grid sudoku Inspired by Flow Fit: Sudoku, a brand-new mobile puzzle game (as of Nov 2019). Background A Latin square is a square grid of side length \$n \$ filled with \$n \$ different symbols, where each row and column contains each symb...

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Giving a set of 33 objects 11 red, 11 yellow and 11 blue, with 5 special towers in which can only contain one color and when a color is placed, all the same color object scores are increased by one point. Ex.( redValue =1; if one red obj placed on special tower, redValue = 2). The cubes can also ...

2 hours later…
2:47 AM
@RedwolfPrograms No, that's not the point. The point is to create a challenge which is theoretically perfectly doable, but completing it is all about finding the obscure features/languages which make it less of an impossible task

@cairdcoinheringaahing I know, I was joking (-:

CMC: Make a program that proves P=NP
"Most creative" wins

3:09 AM
vtc: no objective criterion

3:52 AM
@cairdcoinheringaahing It's very easy. Works in most languages: P=NP
@RedwolfPrograms I envy people who like their own languages.

@A̲̲ From someone whose made (arguably) way too many: the trick is to base them around something you find interesting

@cairdcoinheringaahing Coq: Definition P := 1. Definition NP := 1. Theorem P_is_NP : P = NP. Proof. auto. Qed.

Whenever I learn something new CS/math related, I create a language with that as the core principle

4:17 AM
I've been trying to write a language in the same way I've been trying to write a challenge: waiting for inspiration that won't actually come

1

Each natural number \$n\$ has 10 faces: its decimal representations in bases \$1\$ through to \$10\$. For example, the 10 faces of \$12\$ are \$[111111111111, 1100, 110, 30, 22, 20, 15, 14, 13, 12]\$, and the 10 faces of \$4\$ are \$[1111, 100, 11, 10, 4, 4, 4, 4, 4, 4]\$ We can then say that tw...

@NewMainPosts The best inspiration is to modify other peoples' challenges.

1 hour later…
5:42 AM
@UnrelatedString I just try to find some sort of challenge in the language design, like "it only has three characters" or "it's based on a 3d cube of instructions"
The feeling of waiting for inspiration for a challenge idea though, that's the worst

5:59 AM
For writing challenges, I go through random Wikipedia articles or Google search with pseudorandom keywords until I find something interesting
The topic is mostly math-related in my case

6:55 AM
19

Introduction Let's observe the following sequence (non-negative integers): 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, ... For example, let's take the first three numbers. These are 0, 1, 2. The numbers used in this sequence can be ordered in six different ways: 012 120 021 201 102...

1 hour later…
8:16 AM
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disclaimer: this is extremely experimental and should probably not be taken seriously. Feel free to point out how bad this idea is. This is obviously not completely specified yet. Win the competition king-of-the-hill Write a program that, given two programs, picks the winner. The choice m...

8:26 AM
@NewSandboxedPosts Probably the most chaotic ever, if it goes well.

2 hours later…
10:36 AM
@NewMainPosts Without source restriction, this is 25 bytes in Charcoal: ＦＡ⊞υＥχ⎇κ⍘ι⊕κ×1ιＩΣＥ⊟υ№§υ⁰ι

2 hours later…
12:23 PM
@NewSandboxedPosts The easiest koth that I've ever seen (until OP takes counter-measures).

12:45 PM
@A̲̲ I wouldn't say it is easy.

*simple

1 hour later…
1:54 PM
Reminds me of mine a little, an odd, fun idea that probably wouldn't work in practice

2:11 PM
@RedwolfPrograms A perpetuum mobile?

My sandboxed KoTH, a JS free for all

"an odd, fun idea that probably wouldn't work in practice":
Perpetual motion is motion of bodies that continues indefinitely. A perpetual motion machine is a hypothetical machine that can do work indefinitely without an energy source. This kind of machine is impossible, as it would violate the first or second law of thermodynamics.These laws of thermodynamics apply regardless of the size of the system. For example, the motions and rotations of celestial bodies such as planets may appear perpetual, but are actually subject to many processes that slowly dissipate their kinetic energy, such as solar wind, interstellar medium resistance, gravitational radiation...

Yeah, fair enough comparison

@Adám would probably exacerbate our climate crysis:)

We just have to pretend monopoles exist!

2:21 PM
Wasn't that proven impossible by virtue of magnetic field being equivalent to orthogonal electric field via Lorentz boost?

I love when people say they've created perpetual motion machines that will create "free energy"
Taking energy from the machine would slow it down, no matter how "perpetual"

@flawr Yeah, a run-away PM machine would be very bad.

@RedwolfPrograms But a perpetual motion machine must produce at least as much energy that it is consuming to keep running, doesn't it?

My idea of perpetual motion is a completely frictionless spinning disk. It doesn't lose any energy, or create any

> uses a mono polar magnet
Ugh.

2:23 PM
@Adám You just have to cut these spins in half.

I'd like to know what scientists manage to disprove the laws of thermodynamics, but can only afford a skateboard wheel

Magnetic monopoles work best if painted monochromatic magenta.
4

XD
@Adám I doubt it, since the energy would probably be generated purely as mechanical energy to keep it spinning, so it would just get faster and faster until it either broke or jumped into the future

@RedwolfPrograms Assuming the mechanical energy isn't rotational in an absolute vacuum chamber (which is of course impossible, but whatever), there'll be friction and so the atmosphere will be heated.
Actually, even a flywheel magnetically suspended in vacuum would affect the Earth's rotational energy.

Ah, true. I guess we'd just need a climate activist with a sledgehammer.

2:31 PM
True PMs don't require generation of energy, as they are stable. Why did they need to give it such a totally sci-fi sounding name…
A time crystal or space-time crystal is a structure that repeats in time, as well as in space. Normal three-dimensional crystals have a repeating pattern in space, but remain unchanged as time passes. Time crystals repeat themselves in time as well, leading the crystal to change from moment to moment. If a discrete time translation symmetry is broken (which may be realized in open driven systems) than the system is referred to as a discrete time crystal. A discrete time crystal never reaches thermal equilibrium, as it is a type of non-equilibrium matter, a form of matter proposed in 2012, and first...

Huh, cool
But it'll never beat skateboard wheel with mono polar

@RedwolfPrograms monopole mono polar

2:46 PM
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Pascal's Combination and Permutation Investigation Pascal is rather annoyed. He's claimed ownership of the triangle of cool numbers, but can't see what possible uses it has other than simply being "slightly interesting for a bit". He's turned that job over to you, and you know just the thing tha...

3:41 PM
@Adám Reminds me of the Time Cube.

Classic time cube

4:12 PM
@Adám that is actually used for fly-wheel energy storage

4:27 PM
Hey all, a question inspired by an actual problem. It may make a good CG post, but I want to make sure I'm not missing an obvious solution. The problem is: you have a bunch of small rectangles that you want to scatter "randomly" within a larger rectangle. Think: a bunch of playing cards places in random positions on a table. Constraints: No rotation (the cards edges will remain parallel to the table edges) and no overlap (cards won't overlap each other).
Is there a simply algorithm to achieve this? My initial idea is to scatter dots uniformly (1 dot per card representing the upper left coord for a card) and then do a second pass to deal with removing overlaps.

So what is your desired distribution?
Can they be rotated 90 degrees?

feersum: Uniform or something close-ish to that. It's not too important as long as it "feels" random enough.
"Can they be rotated 90 degrees?" -- No.

Are all small rectangles the same size?

Potato44: Not necessarily.

The naive way of just picking positions for each each card randomly and trying again if it overlaps can fail in some situations. Example: the large rectangle is 4 cards wide and 1 card tall, we want to place 3 cards. The first card(s top-left corner) gets placed at (2/3,0) the second card at (7/3,0). but now we don;t have a large enough space to place the 3rd card.

4:48 PM
In the cramped table limit, the problem of just determining whether the cards can fit at all is NP-hard.
Apparently it's called the "rectangle fit problem".

Interesting. In the real-world case I'm solving the containing rectangle will be "big enough", so the "try the whole thing again" algorithm Potato suggested is probably practical.

In the large table limit you can just do rejection sampling (completely start over if you get an overlap) and get a totally uniform distribution.

1 hour later…
6:03 PM
Yeah, I think that might be enough for me. Thanks guys.

@feersum I think this only applies to rectangles of different sizes

6:51 PM
Sometimes I wonder why I'm allowed to be a programmer.
I just did this: Try it online! and I spent 40 minutes trying to find out why f() wasn't being called.
What does that even do? Why is that allowed?

7:17 PM
@DJMcMayhem void is special kind of a unary operator, it prevents evaluation of its argument

@DJMcMayhem You can add or change two characters to make it work :-)

I could make it work with one character added
@ngn Try it online! works too
Although that's easier to understand I suppose. Declares an integer f and calls it's constructor with an empty expression

oh... in this case i guess the compiler took it as a function declaration, not a unary operator, i was wrong
so, your main re-declares f without doing anything

Ooooh. Kinda like when you use class a; for forward declaration
I've made stupid errors similar to that too many times to count. Like doSomething(callback=f()) rather than doSomething(callback=f)
And JS's incredibly lax type system means that won't error until the last possible minute

@DJMcMayhem You can do stuff like Try it online!

7:25 PM
@ChristianSievers Even better: Try it online!

@DJMcMayhem But that doesn't try to justify your local declaration

today i discovered an elegant way to make c return the result from the last expr in a function: #define _(a...) {R({a;});}
3
and then instead of int f(int x,int y){return x+y;} you write int f(int x,int y)_(x+y)
there could be more exprs/statements before x+y, separated with ;

7:51 PM
@DJMcMayhem I pretty much did the exact same thing once...I tried to set the callback of a function to log, and instead set it to log() (which evaluated to nothing), so I sat there for 20 minutes wondering why it hadn't finished a POST request yet...

@ngn i forgot to say, R is defined as return

@RedwolfPrograms Yeah, type safety is nice