diff --git a/config.json b/config.json index 7f2e473..e684ced 100644 --- a/config.json +++ b/config.json @@ -207,6 +207,14 @@ "prerequisites": [], "difficulty": 3 }, + { + "slug": "isbn-verifier", + "name": "ISBN Verifier", + "uuid": "7d93584a-6367-4b04-af4c-50f893a40a9a", + "practices": [], + "prerequisites": [], + "difficulty": 2 + }, { "slug": "isogram", "name": "Isogram", diff --git a/exercises/practice/isbn-verifier/.docs/instructions.md b/exercises/practice/isbn-verifier/.docs/instructions.md new file mode 100644 index 0000000..4a0244e --- /dev/null +++ b/exercises/practice/isbn-verifier/.docs/instructions.md @@ -0,0 +1,42 @@ +# Instructions + +The [ISBN-10 verification process][isbn-verification] is used to validate book identification numbers. +These normally contain dashes and look like: `3-598-21508-8` + +## ISBN + +The ISBN-10 format is 9 digits (0 to 9) plus one check character (either a digit or an X only). +In the case the check character is an X, this represents the value '10'. +These may be communicated with or without hyphens, and can be checked for their validity by the following formula: + +```text +(d₁ * 10 + d₂ * 9 + d₃ * 8 + d₄ * 7 + d₅ * 6 + d₆ * 5 + d₇ * 4 + d₈ * 3 + d₉ * 2 + d₁₀ * 1) mod 11 == 0 +``` + +If the result is 0, then it is a valid ISBN-10, otherwise it is invalid. + +## Example + +Let's take the ISBN-10 `3-598-21508-8`. +We plug it in to the formula, and get: + +```text +(3 * 10 + 5 * 9 + 9 * 8 + 8 * 7 + 2 * 6 + 1 * 5 + 5 * 4 + 0 * 3 + 8 * 2 + 8 * 1) mod 11 == 0 +``` + +Since the result is 0, this proves that our ISBN is valid. + +## Task + +Given a string the program should check if the provided string is a valid ISBN-10. +Putting this into place requires some thinking about preprocessing/parsing of the string prior to calculating the check digit for the ISBN. + +The program should be able to verify ISBN-10 both with and without separating dashes. + +## Caveats + +Converting from strings to numbers can be tricky in certain languages. +Now, it's even trickier since the check digit of an ISBN-10 may be 'X' (representing '10'). +For instance `3-598-21507-X` is a valid ISBN-10. + +[isbn-verification]: https://en.wikipedia.org/wiki/International_Standard_Book_Number diff --git a/exercises/practice/isbn-verifier/.meta/config.json b/exercises/practice/isbn-verifier/.meta/config.json new file mode 100644 index 0000000..0ee4ae5 --- /dev/null +++ b/exercises/practice/isbn-verifier/.meta/config.json @@ -0,0 +1,19 @@ +{ + "authors": [ + "BNAndras" + ], + "files": { + "solution": [ + "isbn_verifier.vim" + ], + "test": [ + "isbn_verifier.vader" + ], + "example": [ + ".meta/example.vim" + ] + }, + "blurb": "Check if a given string is a valid ISBN-10 number.", + "source": "Converting a string into a number and some basic processing utilizing a relatable real world example.", + "source_url": "https://en.wikipedia.org/wiki/International_Standard_Book_Number#ISBN-10_check_digit_calculation" +} diff --git a/exercises/practice/isbn-verifier/.meta/example.vim b/exercises/practice/isbn-verifier/.meta/example.vim new file mode 100644 index 0000000..fa63b01 --- /dev/null +++ b/exercises/practice/isbn-verifier/.meta/example.vim @@ -0,0 +1,23 @@ +function! IsValid(isbn) abort + let l:digits = substitute(a:isbn, '-', '', 'g') + if len(l:digits) != 10 + return 0 + endif + + let l:sum = 0 + for l:i in range(len(l:digits)) + let l:digit = l:digits[l:i] + if l:digit ==# 'X' + if l:i != len(l:digits) - 1 + return 0 + endif + let l:digit = 10 + endif + if l:digit !~# '\d' + return 0 + endif + let l:sum += l:digit * (10 - i) + endfor + + return l:sum % 11 == 0 +endfunction diff --git a/exercises/practice/isbn-verifier/.meta/tests.toml b/exercises/practice/isbn-verifier/.meta/tests.toml new file mode 100644 index 0000000..6d5a845 --- /dev/null +++ b/exercises/practice/isbn-verifier/.meta/tests.toml @@ -0,0 +1,67 @@ +# This is an auto-generated file. +# +# Regenerating this file via `configlet sync` will: +# - Recreate every `description` key/value pair +# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications +# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion) +# - Preserve any other key/value pair +# +# As user-added comments (using the # character) will be removed when this file +# is regenerated, comments can be added via a `comment` key. + +[0caa3eac-d2e3-4c29-8df8-b188bc8c9292] +description = "valid isbn" + +[19f76b53-7c24-45f8-87b8-4604d0ccd248] +description = "invalid isbn check digit" + +[4164bfee-fb0a-4a1c-9f70-64c6a1903dcd] +description = "valid isbn with a check digit of 10" + +[3ed50db1-8982-4423-a993-93174a20825c] +description = "check digit is a character other than X" + +[9416f4a5-fe01-4b61-a07b-eb75892ef562] +description = "invalid check digit in isbn is not treated as zero" + +[c19ba0c4-014f-4dc3-a63f-ff9aefc9b5ec] +description = "invalid character in isbn is not treated as zero" + +[28025280-2c39-4092-9719-f3234b89c627] +description = "X is only valid as a check digit" + +[f6294e61-7e79-46b3-977b-f48789a4945b] +description = "valid isbn without separating dashes" + +[185ab99b-3a1b-45f3-aeec-b80d80b07f0b] +description = "isbn without separating dashes and X as check digit" + +[7725a837-ec8e-4528-a92a-d981dd8cf3e2] +description = "isbn without check digit and dashes" + +[47e4dfba-9c20-46ed-9958-4d3190630bdf] +description = "too long isbn and no dashes" + +[737f4e91-cbba-4175-95bf-ae630b41fb60] +description = "too short isbn" + +[5458a128-a9b6-4ff8-8afb-674e74567cef] +description = "isbn without check digit" + +[70b6ad83-d0a2-4ca7-a4d5-a9ab731800f7] +description = "check digit of X should not be used for 0" + +[94610459-55ab-4c35-9b93-ff6ea1a8e562] +description = "empty isbn" + +[7bff28d4-d770-48cc-80d6-b20b3a0fb46c] +description = "input is 9 characters" + +[ed6e8d1b-382c-4081-8326-8b772c581fec] +description = "invalid characters are not ignored after checking length" + +[daad3e58-ce00-4395-8a8e-e3eded1cdc86] +description = "invalid characters are not ignored before checking length" + +[fb5e48d8-7c03-4bfb-a088-b101df16fdc3] +description = "input is too long but contains a valid isbn" diff --git a/exercises/practice/isbn-verifier/isbn_verifier.vader b/exercises/practice/isbn-verifier/isbn_verifier.vader new file mode 100644 index 0000000..c19cdfe --- /dev/null +++ b/exercises/practice/isbn-verifier/isbn_verifier.vader @@ -0,0 +1,56 @@ +Execute (valid isbn): + Assert IsValid("3-598-21508-8") + +Execute (invalid isbn check digit): + Assert !IsValid("3-598-21508-9") + +Execute (valid isbn with a check digit of 10): + Assert IsValid("3-598-21507-X") + +Execute (check digit is a character other than X): + Assert !IsValid("3-598-21507-A") + +Execute (invalid check digit in isbn is not treated as zero): + Assert !IsValid("4-598-21507-B") + +Execute (invalid character in isbn is not treated as zero): + Assert !IsValid("3-598-P1581-X") + +Execute (X is only valid as a check digit): + Assert !IsValid("3-598-2X507-9") + +Execute (valid isbn without separating dashes): + Assert IsValid("3598215088") + +Execute (isbn without separating dashes and X as check digit): + Assert IsValid("359821507X") + +Execute (isbn without check digit and dashes): + Assert !IsValid("359821507") + +Execute (too long isbn and no dashes): + Assert !IsValid("3598215078X") + +Execute (too short isbn): + Assert !IsValid("00") + +Execute (isbn without check digit): + Assert !IsValid("3-598-21507") + +Execute (check digit of X should not be used for 0): + Assert !IsValid("3-598-21515-X") + +Execute (empty isbn): + Assert !IsValid("") + +Execute (input is 9 characters): + Assert !IsValid("134456729") + +Execute (invalid characters are not ignored after checking length): + Assert !IsValid("3132P34035") + +Execute (invalid characters are not ignored before checking length): + Assert !IsValid("3598P215088") + +Execute (input is too long but contains a valid isbn): + Assert !IsValid("98245726788") diff --git a/exercises/practice/isbn-verifier/isbn_verifier.vim b/exercises/practice/isbn-verifier/isbn_verifier.vim new file mode 100644 index 0000000..60ad3ea --- /dev/null +++ b/exercises/practice/isbn-verifier/isbn_verifier.vim @@ -0,0 +1,14 @@ +" +" Returns 1 if the given ISBN-10 is valid, 0 otherwise. +" +" Example: +" +" :echo IsValid('3-598-21508-8') +" 1 +" +" :echo IsValid('3-598-21508-9') +" 0 +" +function! IsValid(isbn) abort + " your implementation goes here +endfunction