diff --git a/config.json b/config.json index c5c9d93..673f2e2 100644 --- a/config.json +++ b/config.json @@ -287,6 +287,14 @@ "prerequisites": [], "difficulty": 3 }, + { + "slug": "sieve", + "name": "Sieve", + "uuid": "47e2f7c0-94f7-49a1-b423-32c7e77d0a97", + "practices": [], + "prerequisites": [], + "difficulty": 3 + }, { "slug": "square-root", "name": "Square Root", diff --git a/exercises/practice/sieve/.docs/instructions.md b/exercises/practice/sieve/.docs/instructions.md new file mode 100644 index 0000000..085c0a5 --- /dev/null +++ b/exercises/practice/sieve/.docs/instructions.md @@ -0,0 +1,42 @@ +# Instructions + +Your task is to create a program that implements the Sieve of Eratosthenes algorithm to find all prime numbers less than or equal to a given number. + +A prime number is a number larger than 1 that is only divisible by 1 and itself. +For example, 2, 3, 5, 7, 11, and 13 are prime numbers. +By contrast, 6 is _not_ a prime number as it not only divisible by 1 and itself, but also by 2 and 3. + +To use the Sieve of Eratosthenes, you first create a list of all the numbers between 2 and your given number. +Then you repeat the following steps: + +1. Find the next unmarked number in your list (skipping over marked numbers). + This is a prime number. +2. Mark all the multiples of that prime number as **not** prime. + +You keep repeating these steps until you've gone through every number in your list. +At the end, all the unmarked numbers are prime. + +~~~~exercism/note +The tests don't check that you've implemented the algorithm, only that you've come up with the correct list of primes. +To check you are implementing the Sieve correctly, a good first test is to check that you do not use division or remainder operations. +~~~~ + +## Example + +Let's say you're finding the primes less than or equal to 10. + +- List out 2, 3, 4, 5, 6, 7, 8, 9, 10, leaving them all unmarked. +- 2 is unmarked and is therefore a prime. + Mark 4, 6, 8 and 10 as "not prime". +- 3 is unmarked and is therefore a prime. + Mark 6 and 9 as not prime _(marking 6 is optional - as it's already been marked)_. +- 4 is marked as "not prime", so we skip over it. +- 5 is unmarked and is therefore a prime. + Mark 10 as not prime _(optional - as it's already been marked)_. +- 6 is marked as "not prime", so we skip over it. +- 7 is unmarked and is therefore a prime. +- 8 is marked as "not prime", so we skip over it. +- 9 is marked as "not prime", so we skip over it. +- 10 is marked as "not prime", so we stop as there are no more numbers to check. + +You've examined all numbers and found 2, 3, 5, and 7 are still unmarked, which means they're the primes less than or equal to 10. diff --git a/exercises/practice/sieve/.docs/introduction.md b/exercises/practice/sieve/.docs/introduction.md new file mode 100644 index 0000000..f6c1cf7 --- /dev/null +++ b/exercises/practice/sieve/.docs/introduction.md @@ -0,0 +1,7 @@ +# Introduction + +You bought a big box of random computer parts at a garage sale. +You've started putting the parts together to build custom computers. + +You want to test the performance of different combinations of parts, and decide to create your own benchmarking program to see how your computers compare. +You choose the famous "Sieve of Eratosthenes" algorithm, an ancient algorithm, but one that should push your computers to the limits. diff --git a/exercises/practice/sieve/.meta/Example.roc b/exercises/practice/sieve/.meta/Example.roc new file mode 100644 index 0000000..082aaed --- /dev/null +++ b/exercises/practice/sieve/.meta/Example.roc @@ -0,0 +1,18 @@ +module [primes] + +primes : U64 -> List U64 +primes = \limit -> + if limit < 2 then + [] + else + + help = \candidates, foundPrimes -> + when candidates is + [] -> foundPrimes + [0, .. as rest] -> rest |> help foundPrimes + [prime, .. as rest] -> + List.range { start: After prime, end: At limit, step: prime } + |> List.walk rest \filteredCandidates, multipleOfPrime -> + filteredCandidates |> List.replace (multipleOfPrime - prime - 1) 0 |> .list + |> help (foundPrimes |> List.append prime) + help (List.range { start: At 2, end: At limit }) [] diff --git a/exercises/practice/sieve/.meta/config.json b/exercises/practice/sieve/.meta/config.json new file mode 100644 index 0000000..38fd99d --- /dev/null +++ b/exercises/practice/sieve/.meta/config.json @@ -0,0 +1,19 @@ +{ + "authors": [ + "ageron" + ], + "files": { + "solution": [ + "Sieve.roc" + ], + "test": [ + "sieve-test.roc" + ], + "example": [ + ".meta/Example.roc" + ] + }, + "blurb": "Use the Sieve of Eratosthenes to find all the primes from 2 up to a given number.", + "source": "Sieve of Eratosthenes at Wikipedia", + "source_url": "https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes" +} diff --git a/exercises/practice/sieve/.meta/template.j2 b/exercises/practice/sieve/.meta/template.j2 new file mode 100644 index 0000000..e018b27 --- /dev/null +++ b/exercises/practice/sieve/.meta/template.j2 @@ -0,0 +1,13 @@ +{%- import "generator_macros.j2" as macros with context -%} +{{ macros.canonical_ref() }} +{{ macros.header() }} + +import {{ exercise | to_pascal }} exposing [{{ cases[0]["property"] | to_camel }}] + +{% for case in cases -%} +# {{ case["description"] }} +expect + result = {{ case["property"] | to_camel }} {{ case["input"]["limit"] | to_roc }} + result == {{ case["expected"] | to_roc }} + +{% endfor %} diff --git a/exercises/practice/sieve/.meta/tests.toml b/exercises/practice/sieve/.meta/tests.toml new file mode 100644 index 0000000..fec5e1a --- /dev/null +++ b/exercises/practice/sieve/.meta/tests.toml @@ -0,0 +1,25 @@ +# This is an auto-generated file. +# +# Regenerating this file via `configlet sync` will: +# - Recreate every `description` key/value pair +# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications +# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion) +# - Preserve any other key/value pair +# +# As user-added comments (using the # character) will be removed when this file +# is regenerated, comments can be added via a `comment` key. + +[88529125-c4ce-43cc-bb36-1eb4ddd7b44f] +description = "no primes under two" + +[4afe9474-c705-4477-9923-840e1024cc2b] +description = "find first prime" + +[974945d8-8cd9-4f00-9463-7d813c7f17b7] +description = "find primes up to 10" + +[2e2417b7-3f3a-452a-8594-b9af08af6d82] +description = "limit is prime" + +[92102a05-4c7c-47de-9ed0-b7d5fcd00f21] +description = "find primes up to 1000" diff --git a/exercises/practice/sieve/Sieve.roc b/exercises/practice/sieve/Sieve.roc new file mode 100644 index 0000000..9e267fc --- /dev/null +++ b/exercises/practice/sieve/Sieve.roc @@ -0,0 +1,5 @@ +module [primes] + +primes : U64 -> List U64 +primes = \limit -> + crash "Please implement the 'primes' function" diff --git a/exercises/practice/sieve/sieve-test.roc b/exercises/practice/sieve/sieve-test.roc new file mode 100644 index 0000000..ea6e204 --- /dev/null +++ b/exercises/practice/sieve/sieve-test.roc @@ -0,0 +1,37 @@ +# These tests are auto-generated with test data from: +# https://github.com/exercism/problem-specifications/tree/main/exercises/sieve/canonical-data.json +# File last updated on 2024-09-15 +app [main] { + pf: platform "https://github.com/roc-lang/basic-cli/releases/download/0.15.0/SlwdbJ-3GR7uBWQo6zlmYWNYOxnvo8r6YABXD-45UOw.tar.br", +} + +main = + Task.ok {} + +import Sieve exposing [primes] + +# no primes under two +expect + result = primes 1 + result == [] + +# find first prime +expect + result = primes 2 + result == [2] + +# find primes up to 10 +expect + result = primes 10 + result == [2, 3, 5, 7] + +# limit is prime +expect + result = primes 13 + result == [2, 3, 5, 7, 11, 13] + +# find primes up to 1000 +expect + result = primes 1000 + result == [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 509, 521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593, 599, 601, 607, 613, 617, 619, 631, 641, 643, 647, 653, 659, 661, 673, 677, 683, 691, 701, 709, 719, 727, 733, 739, 743, 751, 757, 761, 769, 773, 787, 797, 809, 811, 821, 823, 827, 829, 839, 853, 857, 859, 863, 877, 881, 883, 887, 907, 911, 919, 929, 937, 941, 947, 953, 967, 971, 977, 983, 991, 997] +