Posts by user
Task I often need to find the factorial of a number or the sum of all numbers up to a number when cheating on math tests. To help me with this, your task is to write $F$, a generalized version of ...
APL (Dyalog Unicode), 33 bytes {×x←⊃(2⌷⍵)(÷⍨(/⍨)0=|)⍺×1⌷⍵:x∇⍵⋄⍺} Try it online! The first case doesn't work because it gets really big, but the other two do. The input is taken on the left a...
Idea shamelessly stolen from caird and rak1507 Shuffle a subset of a list of unique, positive integers with uniform randomness, given the indices of that subset. For example, given the list $[A, B...
Scala, 119 bytes Saved 26 bytes after porting Moshi's solution! _ sortBy("y gree br sc bla oc pe rub ol v f li go ch m cre c s ro a l ru g pu w p o b"split " "indexWhere _.startsWith) Original...
Scala, 78 67 64 bytes Saved 3 bytes thanks to Razetime Stream.iterate(_)(x=>math.pow(x,x%2+.5).toInt).takeWhile(_>1):+1 Try it in Scastie! Stream.iterate(_) //Make an infinite list by r...
APL (Dyalog Unicode), 21 bytes {×⍵-+/∪⍵∨¯1↓⍳⍵}¨∘⍳⊢⌸⍳ Try it online! Returns a matrix (padded with zeroes) where the first row is deficient numbers, the second is perfect numbers, and the thi...
Vyxal, 30 28 25 bytes Saved 1 4 bytes thanks to Aaron Miller ƛ∆K-±";£kɽƛ¥D„£_'t¥=;vṪ,£ Try it Online! A rather pitiful answer, but hey, it works. Gives deficient numbers, then perfect numbers...
Scala -language:postfixOps, 2 bytes 1& Try it online! 1 for odd, 0 for even. Scala, 3 bytes _%2 Try it online! 1 for odd, 0 for even.
Scala 3 and Python 3.8 (pre-release), 2 languages (385 bytes) def String():Any=0 def Int():Any=0 def f(s:String):Any=print(s.replace(chr(81),chr(34)*3+s+chr(34)*3)) class M: f("""def Strin...
Scala, 55 bytes (Stream from 1 map 1.0./scanLeft.0)(_+_)indexWhere _.<= Try it online! Written in a more sane manner: n => Stream.from(1).map(1.0/_).scanLeft(0.0)(_+_).indexWhere(_ &g...
Answering with languages newer than the challenge should absolutely be allowed Most of the time, when a language is newer than a challenge, it's just a coincidence. By not allowing people to answe...
I think "Dangerous" could perhaps stay on. "Outdated" would probably be better off replaced with "Invalid" or something of that sort. I don't think we need "Works for me" or an analog of it at all:...
APL (ngn/apl), 6 bytes {∇¨⍳⍵} Try it online! Dyalog APL and dzaima/APL appear to not give empty vectors for ⍳0, so I used ngn/APL. I don't know how to turn on boxing there, though, so there'...
Scala (-language:postfixOps), 4 solutions 1. Just 256: 256 2. Casting a character: +'Ā' The character Ā is 256 in decimal, and the unary + turns it into an Int. 3. Hashcode of a string: ...
Instead of the code-golf-tips tag, could we tag "Tips for golfing" questions with tips and code-golf instead? They can still be searched for, so I don't see a reason to make a special tag to repres...
Scala, 52 bytes Stream.from(1).filter(x=>x%(x+"":\0)(_+_-48)<1).take Try it in Scastie! Woo, 3 deprecation warnings! (okay, one of them could be fixed but I like to live dangerously) St...
Scala, 41 bytes x=>2 to x forall(d=>x%d+math.sqrt(d)%1>0) Try it online! Pretty straightforward
Japt, 3 bytes ÆßX Try it online! (don't mind the -Q This is Shaggy's solution. ÆßX Æ Make a range [0, input) and map each number X: ß Run this program again on X Japt, 11 8 bytes ...
Python 3.8 (pre-release), 106 95 bytes Saved 11 bytes thanks to Peter Taylor! f=lambda m:sum((-1)**i*x*f([r[:i]+r[i+1:]for r in m[1:]])for i,x in enumerate(m[0]))if m else 1 Try it online! ...
Prolog (SWI), 42 bytes R-S:-S is R*R;R<S,M is R+1,M-S. f(S):-0-S. Try it online!
Japt, 6 3 bytes Cut in half thanks to Shaggy! ¬v1 Try it online! Golfed thanks to Shaggy's interpreter auto-golf feature. ¬v1 ¬ //Square root v1 //Is that an integer?
Scala, 9 bytes _.reverse Try it in Scastie! Explanation: _.reverse _ //The function argument . //Call a method reverse //Reverse the string
