Given a base \$k\$ as well as two indices (also passed in base \$k\$, call them \$s\$ and \$e\$) return a list containing a frequency count of all base-\$k\$ digits occurring between \$s\$ and \$e\$ inclusive. For example, upon input \$k = 10, s = 1, e = 10\$, we would return the list \$[0: 1, 1: 2, 2: 1, 3: 1, 4:1, 5:1, 6:1 , 7:1, 8:1, 9:1]\$. Note that the values in the list should be base \$k\$ as well.

  • 4
    \$\begingroup\$ Hello, and welcome to Code Golf! I like the challenge, but have a few questions: (1) What is the set of characters which should be used for bases larger than 36? (Or is \$k \leq 36\$?) \$\endgroup\$ Nov 2 at 17:17
  • 4
    \$\begingroup\$ Hi, welcome to Code Golf Stack Exchange. Your challenge is quite good, but it could do with a few clarifications, like the comment made by @ . It is reccomended to post challenges in the Sandbox first. \$\endgroup\$ Nov 2 at 17:43
  • \$\begingroup\$ Let's assume \$k \leq 36\$. I will modify my challenge if you can provide me with a good base system for \$k > 36\$. \$\endgroup\$ Nov 2 at 17:48
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    \$\begingroup\$ I think this needs to be much clearer about the strict I/O requirements. For what it's worth I don't think the "characters" question really addresses things, it's a question from someone who planned to use a string representation for their I/O. Sure, IF one is going to use a string of characters there is a limit, but really a base-k number is a list of integers from \$[0,k)\$. Would also be a good idea to show an example in a base other than ten (probably a higher base would show things best). \$\endgroup\$ Nov 2 at 18:48
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    \$\begingroup\$ I didn't notice until now (...), but this challenge doesn't have a scoring criteria (like code-golf). Please consider adding one (otherwise it would be off-topic :p) \$\endgroup\$
    – math scat
    Nov 2 at 20:02

5 Answers 5


Vyxal, 75 bitsv2, 9.375 bytes


Accepts input as \$[s, e], k\$. Takes in indices as a list of digits (to be able to take numbers of bases greater than 10).

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vβ          Convert each index to base 10
  ÷ṡ        Split to stack and push range
    ⁰τ      Convert range to base k
      fĊ    Flatten list and push counts
        ⁰τ  Convert counts list to base k
  • \$\begingroup\$ Hi- your code doesn't fully satisfy the end "values in base k" property. The example you've provided outputs ⟨ ⟨ 2 | 10 ⟩ | ⟨ 1 | 19 ⟩ | ⟨ 0 | 8 ⟩ ⟩ while I want the values (i.e. 10, 19, 8) to be in base 3 as well. \$\endgroup\$ Nov 2 at 17:51
  • \$\begingroup\$ @MichaelKlyachman oh, missed that part. \$\endgroup\$
    – math scat
    Nov 2 at 17:52
  • 1
    \$\begingroup\$ I realised I could take all numbers as a list of digits to make the input format more strict. (and, shaving off some bits in the process :d) \$\endgroup\$
    – math scat
    Nov 2 at 19:01

Python, 163 bytes

def f(k,s,e):b=lambda n:n and b(n//k).lstrip("0")+[str(n%k),chr(n%k+55)][n%k>9]or"0";a="".join(map(b,range(int(s,k),int(e,k)+1)));return{c:b(a.count(c))for c in a}

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Basic solution; a majority of the code is taken up by the helper function converting from base 10 to base \$k\$. I'm sure you could do something clever with a function which directly counts from \$s\$ to \$e\$ in base \$k\$. Only works for bases between 2 and 36.


Ruby, 80 bytes

->k,s,e{(s.to_i(k)..e.to_i(k)).flat_map{_1.digits k}.tally.map{[_1,_2.to_s(k)]}}

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Takes k as integer, s and e as strings in base k. Test cases taken from math scat's Vyxal answer.


Haskell, 148 bytes

import Data.List
k#n|(d,m)<-divMod n k=m:k#d
f k s e=[(last(show x:[[toEnum$x+55]|x>9]),1+length y)|x:y<-group$sort$concatMap(k#)[s..e]]

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Google Sheets, 228 bytes

=let(_,lambda(v,base(v,A1)),r,query(tocol(sort(to_text(split(regexreplace(join(,map(sequence(A3-A2+1,1,A2),_)),"(.)","$1 ")," ")))),"select count(Col1),Col1 group by Col1 label count(Col1)''",0),{map(index(r,,1),_),index(r,,2)})

Put the base in cell A1, start in A2 and end in A3, and the formula in C1.

The same ungolfed:

  _, lambda(v, base(v, A1)), 
  values, sequence(A3 - A2 + 1, 1, A2), 
  string, join(, map(values, _)), 
  digits, tocol(sort(to_text(split(regexreplace(string, "(.)", "$1 "), " ")))), 
  result, query( 
    "select count(Col1), Col1 group by Col1 label count(Col1)''", 
    map(index(result, , 1), _), 
    index(result, , 2) 
parameters results
16 base C 0
1 start 1D 1
200 end 1D 2
1D 3
1D 4
1D 5
1D 6
1D 7
1D 8
1C 9
1C A
1C B
15 C

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