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Comments on How many odd digits?

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How many odd digits?

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Given a positive integer, count its odd digits.

Input

  • An integer from 1 to 999,999,999, inclusive, in any of the following formats:
    • A number (such as an integer or floating point number), like 123.
    • A string, like "123".
    • A sequence of characters (such as an array or list), like ['1', '2', '3'].
    • A sequence of single digit numbers, like [1, 2, 3].

Output

  • The number of odd digits in the input.

Test cases

Test cases are in the format input : output.

1 : 1
2 : 0
3 : 1
4 : 0
5 : 1
6 : 0
7 : 1
8 : 0
9 : 1
10 : 1
11 : 2
12 : 1
13 : 2
14 : 1
15 : 2
16 : 1
17 : 2
18 : 1
19 : 2
20 : 0
111111111 : 9
222222222 : 0
123456789 : 5
999999999 : 9

Scoring

This is a code golf challenge. Your score is the number of bytes in your code. Lowest score for each language wins.

Explanations are optional, but I'm more likely to upvote answers that have one.

code-golf number
posted 3 months ago
3mo ago
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trichoplax‭
1020 reputation 83 17 129 471
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1 comment thread

Input format (5 comments)
Input format
Shaggy‭ wrote 3 months ago
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Any restrictions on the input format? Can we take an array of digits, for example?

trichoplax‭ wrote 3 months ago
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Oh good point. I hadn't thought of that. Usually I like input formats to be flexible as long as the input format doesn't constitute preprocessing. In this case I feel like separating the input into digits is the bulk of the challenge.

I've currently specified input as an integer, so the existing python answer has converted to string before processing. Forbidding input as a string seems difficult (particularly as some answers may take input from STDIN which is always a string). So I'm leaning towards allowing input as an integer or string, but not an array, but some languages have little or no distinction between a string and an array, so I'm not sure if that's best.

I'll avoid relaxing the input format until I've thought about it, as it's easier to make it more flexible than less flexible once answers are posted. Any suggestions of where to draw the line and why?

trichoplax‭ wrote 3 months ago
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Actually allowing input as a string would only take the python answer from 37 bytes to 32, so I was probably overstating "bulk of the challenge".

trichoplax‭ wrote 3 months ago · edited 3 months ago
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Allowing an array of digits (as integers rather than characters) would bring the python answer down to 27 bytes.

I did intend this as a very quick challenge, so I'm now considering allowing input as any of:

  • a number (such as integer or floating point number)
  • a string
  • an array of characters
  • an array of numbers
trichoplax‭ wrote 3 months ago
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I've now edited to make the input format more flexible.

Specifically, yes you can take input as an array of digits.