math sum of squares and square of sum

rust/difference-of-squares/.exercism/config.json

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+{
+  "authors": [
+    "EduardoBautista"
+  ],
+  "contributors": [
+    "ashleygwilliams",
+    "coriolinus",
+    "cwhakes",
+    "eddyp",
+    "EduardoBautista",
+    "efx",
+    "ErikSchierboom",
+    "IanWhitney",
+    "kytrinyx",
+    "leoyvens",
+    "lutostag",
+    "mkantor",
+    "nfiles",
+    "petertseng",
+    "rofrol",
+    "stringparser",
+    "TheDarkula",
+    "xakon",
+    "ZapAnton"
+  ],
+  "files": {
+    "solution": [
+      "src/lib.rs",
+      "Cargo.toml"
+    ],
+    "test": [
+      "tests/difference_of_squares.rs"
+    ],
+    "example": [
+      ".meta/example.rs"
+    ]
+  },
+  "blurb": "Find the difference between the square of the sum and the sum of the squares of the first N natural numbers.",
+  "source": "Problem 6 at Project Euler",
+  "source_url": "https://projecteuler.net/problem=6"
+}

rust/difference-of-squares/.gitignore

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+/target
+Cargo.lock

rust/difference-of-squares/Cargo.toml

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+[package]
+name = "difference_of_squares"
+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/difference-of-squares/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/difference-of-squares/README.md

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+# Difference of Squares
+
+Welcome to Difference of Squares on Exercism's Rust Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+
+## Instructions
+
+Find the difference between the square of the sum and the sum of the squares of the first N natural numbers.
+
+The square of the sum of the first ten natural numbers is
+(1 + 2 + ... + 10)² = 55² = 3025.
+
+The sum of the squares of the first ten natural numbers is
+1² + 2² + ... + 10² = 385.
+
+Hence the difference between the square of the sum of the first ten natural numbers and the sum of the squares of the first ten natural numbers is 3025 - 385 = 2640.
+
+You are not expected to discover an efficient solution to this yourself from first principles; research is allowed, indeed, encouraged.
+Finding the best algorithm for the problem is a key skill in software engineering.
+
+## Source
+
+### Created by
+
+- @EduardoBautista
+
+### Contributed to by
+
+- @ashleygwilliams
+- @coriolinus
+- @cwhakes
+- @eddyp
+- @EduardoBautista
+- @efx
+- @ErikSchierboom
+- @IanWhitney
+- @kytrinyx
+- @leoyvens
+- @lutostag
+- @mkantor
+- @nfiles
+- @petertseng
+- @rofrol
+- @stringparser
+- @TheDarkula
+- @xakon
+- @ZapAnton
+
+### Based on
+
+Problem 6 at Project Euler - https://projecteuler.net/problem=6

rust/difference-of-squares/src/lib.rs

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+pub fn square_of_sum(n: u32) -> u32 {
+    (n * (n + 1) / 2).pow(2)
+}
+
+pub fn sum_of_squares(n: u32) -> u32 {
+    n * (n + 1) * (2 * n + 1) / 6
+}
+
+pub fn difference(n: u32) -> u32 {
+    square_of_sum(n) - sum_of_squares(n)
+}

rust/difference-of-squares/tests/difference_of_squares.rs

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+use difference_of_squares as squares;
+
+#[test]
+fn square_of_sum_1() {
+    assert_eq!(1, squares::square_of_sum(1));
+}
+
+#[test]
+fn square_of_sum_5() {
+    assert_eq!(225, squares::square_of_sum(5));
+}
+
+#[test]
+fn square_of_sum_100() {
+    assert_eq!(25_502_500, squares::square_of_sum(100));
+}
+
+#[test]
+fn sum_of_squares_1() {
+    assert_eq!(1, squares::sum_of_squares(1));
+}
+
+#[test]
+fn sum_of_squares_5() {
+    assert_eq!(55, squares::sum_of_squares(5));
+}
+
+#[test]
+fn sum_of_squares_100() {
+    assert_eq!(338_350, squares::sum_of_squares(100));
+}
+
+#[test]
+fn difference_1() {
+    assert_eq!(0, squares::difference(1));
+}
+
+#[test]
+fn difference_5() {
+    assert_eq!(170, squares::difference(5));
+}
+
+#[test]
+fn difference_100() {
+    assert_eq!(25_164_150, squares::difference(100));
+}