Constructible n-gonscode-golf
Background
A constructible n-gone is a regular polygon with n side that you cand construct with only a compass and an unmarked ruler.Relevant Wikipedia link
As stated by Gauss, the only n for which a n-gon is constructible is a multiple of any distinct Fermat prim...
Pyth, 18 Bytes
?-+vzJEyQ/^E2J-yEJ
Accepts input as a newline-separated list of values.
Try it online!
Explanation:
? If
- the following are not equal:
+vzJE the sum of first and third values (and call the third value J...
0
The Path to the Result
code-golfarithmeticstring (is this last tag correct?)
Input:
A grid of varying size only containing numbers in the range 00-99, the following four characters: ^; >; v; <, and spaces to fill.
Output:
The result of the sum when you follow the path.
How does this work?
...
Tower of Hanoi Hamiltonian Cycle
Every tower of Hanoi has a unique Hamiltonian cycle of length 3ⁿ. The cycle for n=1 is simply 1| | , |1| , | |1 while for n=2 it is as follows:
12 move disc 1 from rod 1 to rod 2
2 1 2 1 3
1 2 1 ...
Two-dimensional programming languages often have mirror commands like / and \ to redirect the instruction pointer on the grid:
>>>>\
v
v
<<<</
In this challenge, you're given an incoming direction and a mirror and you need to determine the outgoing direction.
Rules
The incoming direc...
C# - Massive, Slow, and inefficient solution
Confession: wrote this solution some time ago when the question was still in the sandbox, but it's not very good: you can do better!
Edit: replaced the boring solving with a less boring, more flexible, and generally better method
You run the program...
Perl, 49 bytes
Includes +1 for -p
Run with the 0-based index on STDIN, e.g.
ecce.pl <<< 14
ecce.pl:
#!/usr/bin/perl -p
s,(.)\1*,$&/$1%182 .$1,eg for($_=/$/)x$`;y;19;IV
Magic formulas are so magic.
Normally I would use ($_=//)x$' to make the loop control one byte shorter, but scoring on t...
0
Warn me when charger is unplugged!
So, I've a Compaq Presario V6000 laptop. Two years ago, battery died because of overcharging; So I had to plug charger in order to work with. Without the charger plugged, it runs out of power after ~4 seconds. Unfortunately, today I found out that charger port ...
In graph theory, a connected component (or just component) of an undirected graph is a subgraph in which any two vertices are connected to each other by paths, and which is connected to no additional vertices in the supergraph. For example, the graph shown in the illustration on the right has three connected components. A vertex with no incident edges is itself a connected component. A graph that is itself connected has exactly one connected component, consisting of the whole graph.
== An equivalence relation ==
An alternative way to define connected components involves the equivalence classes...
Python 2, 40 bytes
lambda c,m,k="NWES":k[k.find(c)^(m>k)+1]
Sp3000 saved one byte (.index → .find).
Explanation
We want to map the directions like so:
\
N ⇄⇄⇄⇄⇄⇄⇄ E
⇅ ⇅
⇅ ⇅
/ ⇅ ⇅ /
⇅ ⇅
⇅ ⇅
W ⇄⇄⇄⇄⇄⇄⇄ S
\
We can assign t...
When is their birthday?
Donald Knuth was born in 1938, on the 20th day of Capricorn.
The first day of Capricorn is the 22nd December.
Donald Knuth was born on the 10th of January.
The challenge
Write a program or function which takes three inputs about a person (any other specified order is ...
Challenge description
A Smith number is a composite number whose sum of digits is equal to the sum of sums of digits of its prime factors. Given an integer N, determine if it's a Smith number or not.
The first few Smith numbers are 4, 22, 27, 58, 85, 94, 121, 166, 202, 265, 274, 319, 346, 355, ...
