30
votes
Slash the matrix
MATL, 21 bytes
3XytPJ*-X*Xj~4&1ZIunq
The input is a matrix with 1 for \ and ...
29
votes
29
votes
Is there a single straight line in the matrix?
Python 2, 49 bytes
Takes as input a 2D binary matrix \$ a \$, and its size \$ n \$.
lambda a,n:sorted(map(sum,a+zip(*a)))[-2:]==[1,n]
Try it online!
There may be ...
28
votes
26
votes
Construct the Identity Matrix
MATL, 2 bytes
Xy
A translation of my Octave answer.
Try it online.
A 4 byte version with no built-ins (thanks to Luis Mendo):
...
20
votes
Construct the Identity Matrix
TI-BASIC, 2 bytes
identity(Ans
Fun fact: The shortest way to get a list {N,N} is ...
20
votes
Is it bipartite?
Wolfram Language (Mathematica), 26 25 bytes
Tr[#//.x_:>#.#.Clip@x]<1&
Try it online!
How it works
Given an adjacency matrix A, we find the fixed ...
18
votes
Construct the Identity Matrix
Julia, 9 3 bytes
eye
This is just a built-in function that accepts an integer n and returns an ...
18
votes
Construct the Identity Matrix
APL, 5 bytes
∘.=⍨⍳
This is a monadic function train that accepts an integer on the right and returns the identity matrix.
Try it here
18
votes
To find islands of 1 and 0 in matrix
J, 57 bytes
,&([:(0#@-.~~.@,)](*@[*[:>./((,-)#:i.3)|.!.0])^:_ i.@$)-.
Try it online!
This is one of those where the idea is incredibly simple (and I ...
17
votes
To find islands of 1 and 0 in matrix
APL (Dyalog Unicode), 29 28 bytesSBCS
-1 thanks to @Adám
{≢∪∨.∧⍨⍣≡2>+/↑|∘.-⍨⍸⍵}¨⊂,~∘⊂
Try it online!
⊂,~∘⊂ the matrix ...
16
votes
Construct the Identity Matrix
Python 2, 42 bytes
lambda n:zip(*[iter(([1]+[0]*n)*n)]*n)[:n]
An anonymous function, produces output like ...
16
votes
ASCII texturing
APL (Dyalog Unicode), 20 12 bytesSBCS
-6 bytes through dzaima
Full program. Prompts stdin for:
texture as a list of strings
number of rows in shape matrix
number of columns in shape matrix
indices ...
16
votes
Just Enough Ones
J, 41 bytes
1#.*:=1#.2>[:>@~.@,[:+&,&.>/~i.@!<@A.=@i.
Try it online!
A different take on brute force, which handles up to n=6 on TIO.
Since the ...
16
votes
Count my Pluses
MATL, 29 28 24 bytes
z2Y6ttX*,GbZ+5Mz=z]yytvs
Input is a binary matrix with 1 for '+' and <...
15
votes
14
votes
Construct the Identity Matrix
Octave, 10 4 bytes
@eye
Returns an anonymous function that takes a number n and returns the identity matrix.
14
votes
Decode Faux Braille
Python 3, 181 179 171 167 161 159 bytes
Input by UTF-16 little-endian bytes without BOM. First decompose into columns using bit shifts, split by empty column, then hash them into a lookup table.
-2 ...
14
votes
Mutually Attacking Queens
Python 2, 105 bytes
lambda b:sum(b[i+d::d][:(8,7-i%8,i%8)[d%8%5]].find('1')*int(c)>0for i,c in enumerate(b)for d in[1,7,8,9])
Try it online!
Explanation
We ...
13
votes
Accepted
The last stage of contamination
Since this is basically talking about a cellular automaton I give you..
Golly Quicklife rule, 10 bytes
01234/234V
Input the rule, paste the grid into Golly, run ...
13
votes
Finding Snakes in a Matrix
Python 2, 275 271 264 249 bytes
Saved four bytes by replacing -1 with H and removing one slicing operation (...
13
votes
Is there a left-right connection?
MATLAB/Octave, 115 109 98* bytes
-6 bytes thanks to Luis Mendo
-7 bytes thanks to Luis Mendo
...
13
votes
12
votes
Construct the Identity Matrix
R, 4 bytes
diag
When given a matrix, diag returns the diagonal of the matrix. However, when given an integer ...
12
votes
11
votes
The Binary Square Diagonal Sequence
Husk, 15 14 bytes
zȯḋm←CtNCİ□ṁḋN
Try it online!
Continually prints the results as an infinite list.
Explanation
I wonder whether there's a better way to get ...
11
votes
Accepted
Where is that snake going?
Wolfram Language (Mathematica), 16+83=99 bytes
Library import statement (16 bytes):
<<Combinatorica`
Actual function body (83 bytes):
...
11
votes
Trim that distracting background off!
MATL, 5 bytes
JYaZy
Try it online! Or verify all test cases.
Explanation
...
11
votes
Calculate COVID spread
Jelly, 10 bytes
ŒJạ€ŒṪ§Ṃ€Ṁ
Try it online!
-2 bytes thanks to Sisyphus
Calculate the Manhattan differences from all 0s to all 1s, and the answer is the maximum of ...
11
votes
Calculate COVID spread
Wolfram Language (Mathematica), 90 78 bytes
f=Length@FixedPointList[ListConvolve[CrossMatrix@1,#,{2,2},0,Times,Max]&,#]-2&
Try it online!
-12 bytes, ...
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