New answers tagged chess
2
Wolfram Language, 108 bytes
Tr@MatrixPower[AdjacencyMatrix[4~KnightTourGraph~3~VertexDelete~{10,12}],#2,SparseArray[Mod[#,10,1]->1,10]]&
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You know, there's probably a shorter solution for this, but I enjoy the mathematics of this one. This gets the adjacency matrix for the graph, raises it to the power of the number of jumps, and ...
5
Python 2, 83 bytes
f=lambda s,n:n<1or sum(f(i,n-1)for i in range(10)if`i`+`s`in`0x20cb0e9fd6fe45133e`)
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A recursive solution. Checks for pairs of digits that are a knight's move away by them being consecutive in the hardcoded string 604927618343816729406, written one byte shorter in hex. This string is a palindrome because the adjacency ...
2
T-SQL, 197 bytes
Returns null for no solutions
This can handle 25 hops in 10 seconds
WITH C as(SELECT 0i,1*translate(@n,'37986','11124')x,1q
UNION ALL
SELECT-~i,y,q*(2+1/~(y*~-a))FROM(values(1,4),(1,2),(4,0),(2,1),(4,1),(0,4))x(a,y),c
WHERE a=x AND i<@)
SELECT
sum(q)FROM C
WHERE i=@
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4
Python 3, 88 bytes
f=lambda s,n:n<1or sum(map(f,'46740 021268983 1634 9 7'[int(s)::10].strip(),[n-1]*3))
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-15 bytes thanks to ovs
-2 bytes thanks to Jonathan Allan
2
Java 8, 137 129 bytes
(s,h)->{for(;h-->0;){var t="";for(var c:s.getBytes())t+="46,68,79,48,309,,107,26,13,24".split(",")[c-48];s=t;}return s.length();}
Can probably be golfed a bit more.
Starting digit as a String input, amount of hops as an integer.
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Explanation:
(s,h)->{ // Method ...
2
05AB1E, 24 22 bytes
F•žNjεEÿ¶^²è+%•5¡sèS}g
Amount of hops as first input, and the starting digit as second input.
Try it online or verify all test cases (except for the one with 20 hops, which times out).
Explanation:
F # Loop the first (implicit) input amount of times:
•žNjεEÿ¶^²è+%• # Push compressed integer 46568579548530955107526513524
...
4
Perl 5, (-p) 63 bytes
eval's/./(46,68,79,48,390,"",170,26,13,24)[$&]/ge;'x<>;$_=y///c
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4
Jelly, 29 28 bytes
⁵ṗ’;;Ṣe“¡¿Ṅ\ȷḳ€°ị’Ds2¤ʋƝPɗ€S
A dyadic Link accepting the number of hops on the left and the key on the right which yields the number of paths.
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How?
Forms all length hops decimal numbers, prepends key to each and counts how many have all valid neighbours by lookup in a compressed list. (Note: when hops is zero the fact ...
17
JavaScript (ES6), 86 74 72 bytes
f=(p,n,k=10)=>n?k--&&(306>>(p*2149^k*2149)%71%35&1&&f(k,n-1))+f(p,n,k):1
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71 bytes
Much, much slower.
f=(p,n,k=10)=>n?k--&&(306>>(p*2149^k*2149)%71%35&1)*f(k,n-1)+f(p,n,k):1
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Finding a hash function
We are looking for a function \$h(p,k)\$ ...
4
Charcoal, 31 bytes
ＦＮ≔⭆η§⪪”)‴↘Ｓ‴Ｐeυ!&q]3⁰4”¶ＩκηＩＬη
Try it online! Link is to verbose version of code. Takes the number of hops as the first input. Too slow for large numbers of hops. Explanation:
ＦＮ
Input the number of hops and repeat that many times.
≔⭆η§⪪”)‴↘Ｓ‴Ｐeυ!&q]3⁰4”¶Ｉκη
Map over every character in the string and list its possible next hops....
6
Stax, 63 bytes
÷Qa9═wë•Θ╣äUuâ£▼+∙8WU▓kw≈▲!.┤α@∟┐₧╨═ºî⌂z▼0╬⌂6╕ú▄O&⌂¼^Mgâ╗╕.î¡☼:
Run and debug it
Takes input as <position before> <piece type> [<other pieces>] <position after>.
Unpacked:
;x\EE-c:+"=+-"@s|aaE=s,h?$+Ydx]+MEsxh|I@|oc%vcaHX-xn^$'-?'+?z?,b'S<*!,h$*++y+
Run and debug it
Explanation:
The first part ...
1
05AB1E, 41 bytes
Ç`+É•wH˜OÝ•44в*s11%©è•2ĀpakΩÕðβ•₂в2ä+sè®è
Try it online or verify all test cases.
Explanation:
Ç # Convert the (implicit) input to a list of codepoint integers
` # Pop and push the four integers separated to the stack
+ # Add the top two together (column+row)
É ...
2
JavaScript (Node.js), 84 bytes
s=>[a=~"0628"[[C,P,F,R]=Buffer(s),i=P%11%7],b=-"63682"[i]||4][C&1]+(F+R&1?45-a-b:19)
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How?
The color, the piece, the file and the rank characters are turned into ASCII codes which are saved into \$C\$, \$P\$, \$F\$ and \$R\$ respectively.
We compute the piece index \$i=(P \bmod 11)\...
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