diff --git a/zig/luhn/.exercism/config.json b/zig/luhn/.exercism/config.json new file mode 100644 index 0000000..48777b9 --- /dev/null +++ b/zig/luhn/.exercism/config.json @@ -0,0 +1,19 @@ +{ + "authors": [ + "ee7" + ], + "files": { + "solution": [ + "luhn.zig" + ], + "test": [ + "test_luhn.zig" + ], + "example": [ + ".meta/example.zig" + ] + }, + "blurb": "Given a number determine whether or not it is valid per the Luhn formula.", + "source": "The Luhn Algorithm on Wikipedia", + "source_url": "https://en.wikipedia.org/wiki/Luhn_algorithm" +} diff --git a/zig/luhn/.exercism/metadata.json b/zig/luhn/.exercism/metadata.json new file mode 100644 index 0000000..1830286 --- /dev/null +++ b/zig/luhn/.exercism/metadata.json @@ -0,0 +1 @@ +{"track":"zig","exercise":"luhn","id":"5c3683c495e143e98cf457b99607c9fb","url":"https://exercism.org/tracks/zig/exercises/luhn","handle":"Chomp1295","is_requester":true,"auto_approve":false} \ No newline at end of file diff --git a/zig/luhn/HELP.md b/zig/luhn/HELP.md new file mode 100644 index 0000000..d1174eb --- /dev/null +++ b/zig/luhn/HELP.md @@ -0,0 +1,53 @@ +# Help + +## Running the tests + +Write your code in `.zig`. + +To run the tests for an exercise, run: + +```bash +zig test test_exercise_name.zig +``` + +in the exercise's root directory (replacing `exercise_name` with the name of the exercise). + +## Submitting your solution + +You can submit your solution using the `exercism submit luhn.zig` command. +This command will upload your solution to the Exercism website and print the solution page's URL. + +It's possible to submit an incomplete solution which allows you to: + +- See how others have completed the exercise +- Request help from a mentor + +## Need to get help? + +If you'd like help solving the exercise, check the following pages: + +- The [Zig track's documentation](https://exercism.org/docs/tracks/zig) +- The [Zig track's programming category on the forum](https://forum.exercism.org/c/programming/zig) +- [Exercism's programming category on the forum](https://forum.exercism.org/c/programming/5) +- The [Frequently Asked Questions](https://exercism.org/docs/using/faqs) + +Should those resources not suffice, you could submit your (incomplete) solution to request mentoring. + +- [The Zig Programming Language Documentation][documentation] is a great overview of all of the language features that Zig provides to those who use it. +- [Zig Guide][zig-guide] is an excellent primer that explains the language features that Zig has to offer. +- [Ziglings][ziglings] is highly recommended. + Learn Zig by fixing tiny broken programs. +- [The Zig Programming Language Discord][discord-zig] is the main [Discord][discord]. + It provides a great way to get in touch with the Zig community at large, and get some quick, direct help for any Zig related problem. +- [#zig][irc] on irc.freenode.net is the main Zig IRC channel. +- [/r/Zig][reddit] is the main Zig subreddit. +- [Stack Overflow][stack-overflow] can be used to discover code snippets and solutions to problems that may have already asked and maybe solved by others. + +[discord]: https://discordapp.com +[discord-zig]: https://discord.com/invite/gxsFFjE +[documentation]: https://ziglang.org/documentation/master +[irc]: https://webchat.freenode.net/?channels=%23zig +[reddit]: https://www.reddit.com/r/Zig +[stack-overflow]: https://stackoverflow.com/questions/tagged/zig +[zig-guide]: https://zig.guide/ +[ziglings]: https://codeberg.org/ziglings/exercises \ No newline at end of file diff --git a/zig/luhn/README.md b/zig/luhn/README.md new file mode 100644 index 0000000..0ada4b6 --- /dev/null +++ b/zig/luhn/README.md @@ -0,0 +1,79 @@ +# Luhn + +Welcome to Luhn on Exercism's Zig Track. +If you need help running the tests or submitting your code, check out `HELP.md`. + +## Instructions + +Given a number determine whether or not it is valid per the Luhn formula. + +The [Luhn algorithm][luhn] is a simple checksum formula used to validate a variety of identification numbers, such as credit card numbers and Canadian Social Insurance Numbers. + +The task is to check if a given string is valid. + +## Validating a Number + +Strings of length 1 or less are not valid. +Spaces are allowed in the input, but they should be stripped before checking. +All other non-digit characters are disallowed. + +### Example 1: valid credit card number + +```text +4539 3195 0343 6467 +``` + +The first step of the Luhn algorithm is to double every second digit, starting from the right. +We will be doubling + +```text +4_3_ 3_9_ 0_4_ 6_6_ +``` + +If doubling the number results in a number greater than 9 then subtract 9 from the product. +The results of our doubling: + +```text +8569 6195 0383 3437 +``` + +Then sum all of the digits: + +```text +8+5+6+9+6+1+9+5+0+3+8+3+3+4+3+7 = 80 +``` + +If the sum is evenly divisible by 10, then the number is valid. +This number is valid! + +### Example 2: invalid credit card number + +```text +8273 1232 7352 0569 +``` + +Double the second digits, starting from the right + +```text +7253 2262 5312 0539 +``` + +Sum the digits + +```text +7+2+5+3+2+2+6+2+5+3+1+2+0+5+3+9 = 57 +``` + +57 is not evenly divisible by 10, so this number is not valid. + +[luhn]: https://en.wikipedia.org/wiki/Luhn_algorithm + +## Source + +### Created by + +- @ee7 + +### Based on + +The Luhn Algorithm on Wikipedia - https://en.wikipedia.org/wiki/Luhn_algorithm \ No newline at end of file diff --git a/zig/luhn/luhn.zig b/zig/luhn/luhn.zig new file mode 100644 index 0000000..21de601 --- /dev/null +++ b/zig/luhn/luhn.zig @@ -0,0 +1,29 @@ +const std = @import("std"); +const ascii = std.ascii; + +pub fn isValid(s: []const u8) bool { + var idx: usize = s.len; + var luhn_idx: usize = 1; + var total: u64 = 0; + + while (idx > 0) { + idx -= 1; + if (s[idx] == 32) continue; + if (!ascii.isDigit(s[idx])) { + return false; + } + + var curr: u8 = s[idx] - 48; + if (luhn_idx % 2 == 0) { + curr *= 2; + if (curr > 9) { + curr -= 9; + } + } + total += curr; + luhn_idx += 1; + } + + if (luhn_idx <= 2) return false; + return total % 10 == 0; +} diff --git a/zig/luhn/test_luhn.zig b/zig/luhn/test_luhn.zig new file mode 100644 index 0000000..12281ce --- /dev/null +++ b/zig/luhn/test_luhn.zig @@ -0,0 +1,92 @@ +const std = @import("std"); +const testing = std.testing; + +const isValid = @import("luhn.zig").isValid; + +test "single digit strings cannot be valid" { + try testing.expect(!isValid("1")); +} + +test "a single zero is invalid" { + try testing.expect(!isValid("0")); +} + +test "a simple valid SIN that remains valid if reversed" { + try testing.expect(isValid("059")); +} + +test "a simple valid SIN that becomes invalid if reversed" { + try testing.expect(isValid("59")); +} + +test "a valid Canadian SIN" { + try testing.expect(isValid("055 444 285")); +} + +test "invalid Canadian SIN" { + try testing.expect(!isValid("055 444 286")); +} + +test "invalid credit card" { + try testing.expect(!isValid("8273 1232 7352 0569")); +} + +test "invalid long number with an even remainder" { + try testing.expect(!isValid("1 2345 6789 1234 5678 9012")); +} + +test "invalid long number with a remainder divisible by 5" { + try testing.expect(!isValid("1 2345 6789 1234 5678 9013")); +} + +test "valid number with an even number of digits" { + try testing.expect(isValid("095 245 88")); +} + +test "valid number with an odd number of spaces" { + try testing.expect(isValid("234 567 891 234")); +} + +test "valid strings with a non-digit added at the end become invalid" { + try testing.expect(!isValid("059a")); +} + +test "valid strings with punctuation included become invalid" { + try testing.expect(!isValid("055-444-285")); +} + +test "valid strings with symbols included become invalid" { + try testing.expect(!isValid("055# 444$ 285")); +} + +test "single zero with space is invalid" { + try testing.expect(!isValid(" 0")); +} + +test "more than a single zero is valid" { + try testing.expect(isValid("0000 0")); +} + +test "input digit 9 is correctly converted to output digit 9" { + try testing.expect(isValid("091")); +} + +test "very long input is valid" { + try testing.expect(isValid("9999999999 9999999999 9999999999 9999999999")); +} + +test "valid luhn with an odd number of digits and non zero first digit" { + try testing.expect(isValid("109")); +} + +test "using ascii value for non-doubled non-digit isn't allowed" { + try testing.expect(!isValid("055b 444 285")); +} + +test "using ascii value for doubled non-digit isn't allowed" { + try testing.expect(!isValid(":9")); +} + +test "non-numeric, non-space char in the middle with a sum that's divisible by 10 isn't allowed" { + try testing.expect(!isValid("59%59")); +}