sum-of-multiples

rust/sum-of-multiples/.exercism/config.json

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+{
+  "authors": [
+    "IanWhitney"
+  ],
+  "contributors": [
+    "coriolinus",
+    "cwhakes",
+    "eddyp",
+    "efx",
+    "ErikSchierboom",
+    "GoneUp",
+    "hekrause",
+    "leoyvens",
+    "lutostag",
+    "mkantor",
+    "nfiles",
+    "petertseng",
+    "rofrol",
+    "sshine",
+    "stringparser",
+    "xakon",
+    "ZapAnton"
+  ],
+  "files": {
+    "solution": [
+      "src/lib.rs",
+      "Cargo.toml"
+    ],
+    "test": [
+      "tests/sum_of_multiples.rs"
+    ],
+    "example": [
+      ".meta/example.rs"
+    ]
+  },
+  "blurb": "Given a number, find the sum of all the multiples of particular numbers up to but not including that number.",
+  "source": "A variation on Problem 1 at Project Euler",
+  "source_url": "https://projecteuler.net/problem=1"
+}

rust/sum-of-multiples/.gitignore

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+/target
+Cargo.lock

rust/sum-of-multiples/Cargo.toml

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+[package]
+name = "sum_of_multiples"
+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/sum-of-multiples/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/sum-of-multiples/README.md

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+# Sum of Multiples
+
+Welcome to Sum of Multiples on Exercism's Rust Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+
+## Introduction
+
+You work for a company that makes an online, fantasy-survival game.
+
+When a player finishes a level, they are awarded energy points.
+The amount of energy awarded depends on which magical items the player found while exploring that level.
+
+## Instructions
+
+Your task is to write the code that calculates the energy points that get awarded to players when they complete a level.
+
+The points awarded depend on two things:
+
+- The level (a number) that the player completed.
+- The base value of each magical item collected by the player during that level.
+
+The energy points are awarded according to the following rules:
+
+1. For each magical item, take the base value and find all the multiples of that value that are less than the level number.
+2. Combine the sets of numbers.
+3. Remove any duplicates.
+4. Calculate the sum of all the numbers that are left.
+
+Let's look at an example:
+
+**The player completed level 20 and found two magical items with base values of 3 and 5.**
+
+To calculate the energy points earned by the player, we need to find all the unique multiples of these base values that are less than level 20.
+
+- Multiples of 3 less than 20: `{3, 6, 9, 12, 15, 18}`
+- Multiples of 5 less than 20: `{5, 10, 15}`
+- Combine the sets and remove duplicates: `{3, 5, 6, 9, 10, 12, 15, 18}`
+- Sum the unique multiples: `3 + 5 + 6 + 9 + 10 + 12 + 15 + 18 = 78`
+- Therefore, the player earns **78** energy points for completing level 20 and finding the two magical items with base values of 3 and 5.
+
+## Source
+
+### Created by
+
+- @IanWhitney
+
+### Contributed to by
+
+- @coriolinus
+- @cwhakes
+- @eddyp
+- @efx
+- @ErikSchierboom
+- @GoneUp
+- @hekrause
+- @leoyvens
+- @lutostag
+- @mkantor
+- @nfiles
+- @petertseng
+- @rofrol
+- @sshine
+- @stringparser
+- @xakon
+- @ZapAnton
+
+### Based on
+
+A variation on Problem 1 at Project Euler - https://projecteuler.net/problem=1

rust/sum-of-multiples/src/lib.rs

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+use std::collections::HashSet;
+
+pub fn sum_of_multiples(limit: u32, factors: &[u32]) -> u32 {
+    factors
+        .iter()
+        .copied()
+        .filter(|&x| 0 < x)
+        .flat_map(|num| (num..limit).step_by(num as usize))
+        .collect::<HashSet<_>>()
+        .iter()
+        .sum()
+}

rust/sum-of-multiples/tests/sum_of_multiples.rs

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+use sum_of_multiples::*;
+
+#[test]
+fn no_multiples_within_limit() {
+    let factors = &[3, 5];
+    let limit = 1;
+    let output = sum_of_multiples(limit, factors);
+    let expected = 0;
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn one_factor_has_multiples_within_limit() {
+    let factors = &[3, 5];
+    let limit = 4;
+    let output = sum_of_multiples(limit, factors);
+    let expected = 3;
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn more_than_one_multiple_within_limit() {
+    let factors = &[3];
+    let limit = 7;
+    let output = sum_of_multiples(limit, factors);
+    let expected = 9;
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn more_than_one_factor_with_multiples_within_limit() {
+    let factors = &[3, 5];
+    let limit = 10;
+    let output = sum_of_multiples(limit, factors);
+    let expected = 23;
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn each_multiple_is_only_counted_once() {
+    let factors = &[3, 5];
+    let limit = 100;
+    let output = sum_of_multiples(limit, factors);
+    let expected = 2_318;
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn a_much_larger_limit() {
+    let factors = &[3, 5];
+    let limit = 1_000;
+    let output = sum_of_multiples(limit, factors);
+    let expected = 233_168;
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn three_factors() {
+    let factors = &[7, 13, 17];
+    let limit = 20;
+    let output = sum_of_multiples(limit, factors);
+    let expected = 51;
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn factors_not_relatively_prime() {
+    let factors = &[4, 6];
+    let limit = 15;
+    let output = sum_of_multiples(limit, factors);
+    let expected = 30;
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn some_pairs_of_factors_relatively_prime_and_some_not() {
+    let factors = &[5, 6, 8];
+    let limit = 150;
+    let output = sum_of_multiples(limit, factors);
+    let expected = 4_419;
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn one_factor_is_a_multiple_of_another() {
+    let factors = &[5, 25];
+    let limit = 51;
+    let output = sum_of_multiples(limit, factors);
+    let expected = 275;
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn much_larger_factors() {
+    let factors = &[43, 47];
+    let limit = 10_000;
+    let output = sum_of_multiples(limit, factors);
+    let expected = 2_203_160;
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn all_numbers_are_multiples_of_1() {
+    let factors = &[1];
+    let limit = 100;
+    let output = sum_of_multiples(limit, factors);
+    let expected = 4_950;
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn no_factors_means_an_empty_sum() {
+    let factors = &[];
+    let limit = 10_000;
+    let output = sum_of_multiples(limit, factors);
+    let expected = 0;
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn the_only_multiple_of_0_is_0() {
+    let factors = &[0];
+    let limit = 1;
+    let output = sum_of_multiples(limit, factors);
+    let expected = 0;
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn the_factor_0_does_not_affect_the_sum_of_multiples_of_other_factors() {
+    let factors = &[3, 0];
+    let limit = 4;
+    let output = sum_of_multiples(limit, factors);
+    let expected = 3;
+    assert_eq!(output, expected);
+}
+
+#[test]
+fn solutions_using_include_exclude_must_extend_to_cardinality_greater_than_3() {
+    let factors = &[2, 3, 5, 7, 11];
+    let limit = 10_000;
+    let output = sum_of_multiples(limit, factors);
+    let expected = 39_614_537;
+    assert_eq!(output, expected);
+}