r/difference-of-squares: download exercise

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

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+{
+  "authors": [
+    "cmiller01"
+  ],
+  "contributors": [
+    "jonmcalder",
+    "katrinleinweber",
+    "kytrinyx",
+    "Scientifica96",
+    "zacchaeusluke"
+  ],
+  "files": {
+    "solution": [
+      "difference-of-squares.R"
+    ],
+    "test": [
+      "test_difference-of-squares.R"
+    ],
+    "example": [
+      ".meta/example.R"
+    ]
+  },
+  "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"
+}

r/difference-of-squares/.exercism/metadata.json

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+{"track":"r","exercise":"difference-of-squares","id":"42fd99e2e04547a083cda1f2e6264fa3","url":"https://exercism.org/tracks/r/exercises/difference-of-squares","handle":"vpayno","is_requester":true,"auto_approve":false}

r/difference-of-squares/HELP.md

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+# Help
+
+## Running the tests
+
+Tests require the `{testthat}` package to be installed in R.
+To run the tests for an exercise, simply execute the `test_<exercise_name>.R` script from within the exercise's directory.
+
+This can be conveniently done with [testthat's `auto_test` function](https://testthat.r-lib.org/reference/auto_test.html). Because exercism code and tests are in the same folder, use this same path for both `code_path` and `test_path` parameters. On the command-line, you can also run `Rscript test_<exercise_name>.R`.
+
+See the [tests page](https://exercism.org/docs/tracks/r/tests) for more information.
+
+## Submitting your solution
+
+You can submit your solution using the `exercism submit difference-of-squares.R` 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 [R track's documentation](https://exercism.org/docs/tracks/r)
+- The [R track's programming category on the forum](https://forum.exercism.org/c/programming/r)
+- [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.
+
+To get help if you're having trouble, you can try one of the following resources:
+
+- [StackOverflow](https://stackoverflow.com/questions/tagged/r) can be used to search for your problem and see if it has been answered already. You can also ask and answer questions.
+- [#rstats](https://twitter.com/search?q=%23rstats) is the hashtag to use if you are asking for help or guidance on Twitter. The R community is very active on Twitter and always try to help those who are new to R.
+- [/r/rstats](https://www.reddit.com/r/rstats) is the R subreddit.
+- [RStudio Community](https://community.rstudio.com/) is another active and helpful R community.

r/difference-of-squares/README.md

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+# Difference of Squares
+
+Welcome to Difference of Squares on Exercism's R 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
+
+- @cmiller01
+
+### Contributed to by
+
+- @jonmcalder
+- @katrinleinweber
+- @kytrinyx
+- @Scientifica96
+- @zacchaeusluke
+
+### Based on
+
+Problem 6 at Project Euler - https://projecteuler.net/problem=6

r/difference-of-squares/difference-of-squares.R

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+# this is a stub function that takes a natural_number
+# and should return the difference-of-squares as described
+# in the README.md
+difference_of_squares <- function(natural_number) {
+}

r/difference-of-squares/test_difference-of-squares.R

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+source("./difference-of-squares.R")
+library(testthat)
+
+test_that("difference of squares 0", {
+  input <- 0
+  expect_equal(difference_of_squares(input), 0)
+})
+
+test_that("difference of squares 5", {
+  input <- 5
+  expect_equal(difference_of_squares(input), 170)
+})
+
+test_that("difference of squares 10", {
+  input <- 10
+  expect_equal(difference_of_squares(input), 2640)
+})
+
+test_that("difference of squares 100", {
+  input <- 100
+  expect_equal(difference_of_squares(input), 25164150)
+})