armstrong numbers

rust/armstrong-numbers/.exercism/config.json

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+{
+  "authors": [
+    "shingtaklam1324"
+  ],
+  "contributors": [
+    "AndrewKvalheim",
+    "coriolinus",
+    "cwhakes",
+    "eddyp",
+    "efx",
+    "ErikSchierboom",
+    "lutostag",
+    "ocstl",
+    "petertseng",
+    "rofrol",
+    "sputnick1124",
+    "stringparser",
+    "xakon",
+    "ZapAnton"
+  ],
+  "files": {
+    "solution": [
+      "src/lib.rs",
+      "Cargo.toml"
+    ],
+    "test": [
+      "tests/armstrong_numbers.rs"
+    ],
+    "example": [
+      ".meta/example.rs"
+    ]
+  },
+  "blurb": "Determine if a number is an Armstrong number.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/Narcissistic_number"
+}

rust/armstrong-numbers/.gitignore

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+/target
+Cargo.lock

rust/armstrong-numbers/Cargo.toml

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+[package]
+name = "armstrong_numbers"
+version = "0.1.0"
+edition = "2024"
+
+# Not all libraries from crates.io are available in Exercism's test runner.
+# The full list of available libraries is here:
+# https://github.com/exercism/rust-test-runner/blob/main/local-registry/Cargo.toml
+[dependencies]

rust/armstrong-numbers/HELP.md

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+# Help
+
+## Running the tests
+
+Execute the tests with:
+
+```bash
+$ cargo test
+```
+
+All but the first test have been ignored. After you get the first test to
+pass, open the tests source file which is located in the `tests` directory
+and remove the `#[ignore]` flag from the next test and get the tests to pass
+again. Each separate test is a function with `#[test]` flag above it.
+Continue, until you pass every test.
+
+If you wish to run _only ignored_ tests without editing the tests source file, use:
+
+```bash
+$ cargo test -- --ignored
+```
+
+If you are using Rust 1.51 or later, you can run _all_ tests with
+
+```bash
+$ cargo test -- --include-ignored
+```
+
+To run a specific test, for example `some_test`, you can use:
+
+```bash
+$ cargo test some_test
+```
+
+If the specific test is ignored, use:
+
+```bash
+$ cargo test some_test -- --ignored
+```
+
+To learn more about Rust tests refer to the online [test documentation][rust-tests].
+
+[rust-tests]: https://doc.rust-lang.org/book/ch11-02-running-tests.html
+
+## Submitting your solution
+
+You can submit your solution using the `exercism submit src/lib.rs Cargo.toml` 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 [Rust track's documentation](https://exercism.org/docs/tracks/rust)
+- The [Rust track's programming category on the forum](https://forum.exercism.org/c/programming/rust)
+- [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.
+
+## Rust Installation
+
+Refer to the [exercism help page][help-page] for Rust installation and learning
+resources.
+
+## Submitting the solution
+
+Generally you should submit all files in which you implemented your solution (`src/lib.rs` in most cases). If you are using any external crates, please consider submitting the `Cargo.toml` file. This will make the review process faster and clearer.
+
+## Feedback, Issues, Pull Requests
+
+Head to [the forum](https://forum.exercism.org/c/programming/rust/) and create a post to provide feedback about an exercise or if you want to help implement new exercises.
+Members of the rust track team are happy to help!
+
+The GitHub [track repository][github] is the home for all of the Rust exercises.
+
+If you want to know more about Exercism, take a look at the [contribution guide].
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.
+
+[help-page]: https://exercism.org/tracks/rust/learning
+[github]: https://github.com/exercism/rust
+[contribution guide]: https://exercism.org/docs/community/contributors

rust/armstrong-numbers/README.md

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+# Armstrong Numbers
+
+Welcome to Armstrong Numbers on Exercism's Rust Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+
+## Instructions
+
+An [Armstrong number][armstrong-number] is a number that is the sum of its own digits each raised to the power of the number of digits.
+
+For example:
+
+- 9 is an Armstrong number, because `9 = 9^1 = 9`
+- 10 is _not_ an Armstrong number, because `10 != 1^2 + 0^2 = 1`
+- 153 is an Armstrong number, because: `153 = 1^3 + 5^3 + 3^3 = 1 + 125 + 27 = 153`
+- 154 is _not_ an Armstrong number, because: `154 != 1^3 + 5^3 + 4^3 = 1 + 125 + 64 = 190`
+
+Write some code to determine whether a number is an Armstrong number.
+
+[armstrong-number]: https://en.wikipedia.org/wiki/Narcissistic_number
+
+## Source
+
+### Created by
+
+- @shingtaklam1324
+
+### Contributed to by
+
+- @AndrewKvalheim
+- @coriolinus
+- @cwhakes
+- @eddyp
+- @efx
+- @ErikSchierboom
+- @lutostag
+- @ocstl
+- @petertseng
+- @rofrol
+- @sputnick1124
+- @stringparser
+- @xakon
+- @ZapAnton
+
+### Based on
+
+Wikipedia - https://en.wikipedia.org/wiki/Narcissistic_number

rust/armstrong-numbers/src/lib.rs

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+pub fn is_armstrong_number(num: u32) -> bool {
+    if 0 == num {
+        return true;
+    }
+    let count = (num as f64).log10().floor() as u32 + 1;
+
+    let sum: u32 = (1..=count)
+        .map(|i| num % 10_u32.pow(i) / 10_u32.pow(i - 1))
+        .map(|x| (x).pow(count))
+        .sum();
+    sum == num
+}

rust/armstrong-numbers/tests/armstrong_numbers.rs

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+use armstrong_numbers::*;
+
+#[test]
+fn zero_is_an_armstrong_number() {
+    assert!(is_armstrong_number(0))
+}
+
+#[test]
+fn single_digit_numbers_are_armstrong_numbers() {
+    assert!(is_armstrong_number(5))
+}
+
+#[test]
+fn there_are_no_two_digit_armstrong_numbers() {
+    assert!(!is_armstrong_number(10))
+}
+
+#[test]
+fn three_digit_number_that_is_an_armstrong_number() {
+    assert!(is_armstrong_number(153))
+}
+
+#[test]
+fn three_digit_number_that_is_not_an_armstrong_number() {
+    assert!(!is_armstrong_number(100))
+}
+
+#[test]
+fn four_digit_number_that_is_an_armstrong_number() {
+    assert!(is_armstrong_number(9_474))
+}
+
+#[test]
+fn four_digit_number_that_is_not_an_armstrong_number() {
+    assert!(!is_armstrong_number(9_475))
+}
+
+#[test]
+fn seven_digit_number_that_is_an_armstrong_number() {
+    assert!(is_armstrong_number(9_926_315))
+}
+
+#[test]
+fn seven_digit_number_that_is_not_an_armstrong_number() {
+    assert!(!is_armstrong_number(9_926_314))
+}