Add sieve (#144)

config.json

@@ -381,6 +381,14 @@
         "prerequisites": [],
         "difficulty": 3
       },
+      {
+        "slug": "sieve",
+        "name": "Sieve",
+        "uuid": "dcb4854d-0ec9-48a9-82ec-3e60f9f0433e",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 2
+      },
       {
         "slug": "space-age",
         "name": "Space Age",

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.

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.

exercises/practice/sieve/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "BNAndras"
+  ],
+  "files": {
+    "solution": [
+      "src/sieve.art"
+    ],
+    "test": [
+      "tests/test-sieve.art"
+    ],
+    "example": [
+      ".meta/src/example.art"
+    ]
+  },
+  "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"
+}

exercises/practice/sieve/.meta/src/example.art

@@ -0,0 +1,23 @@
+primes: function [limit][
+    if limit < 2 -> return []
+    isPrime: array.of: inc limit true
+    isPrime\0: false
+    isPrime\1: false
+
+    loop 2..limit 'num [
+        if isPrime\[num] [
+            multiple: num * num
+            while [multiple =< limit] [
+                isPrime\[multiple]: false
+                'multiple + num
+            ]
+        ]
+    ]
+
+    results: []
+    loop 2..limit 'num [
+        if isPrime\[num] -> 'results ++ num
+    ]
+
+    results
+]

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"

exercises/practice/sieve/src/sieve.art

@@ -0,0 +1,3 @@
+primes: function [limit][
+    panic "Please implement the primes function"
+]

exercises/practice/sieve/tester.art

@@ -0,0 +1,3 @@
+import {unitt}!
+
+runTests.failFast findTests "tests"

exercises/practice/sieve/tests/test-sieve.art

@@ -0,0 +1,47 @@
+import {unitt}!
+import {src/sieve}!
+
+suite "Sieve" [
+  test "no primes under two" [
+    results: primes 1
+    expected: []
+    assert -> expected = results
+  ]
+
+  test.skip "find first prime" [
+    results: primes 2
+    expected: [2]
+    assert -> expected = results
+  ]
+
+  test.skip "find primes up to 10" [
+    results: primes 10
+    expected: [2 3 5 7]
+    assert -> expected = results
+  ]
+
+  test.skip "limit is prime" [
+    results: primes 13
+    expected: [2 3 5 7 11 13]
+    assert -> expected = results
+  ]
+
+  test.skip "find primes up to 1000" [
+    results: primes 1000
+    expected: [
+        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
+    ]
+    assert -> expected = results
+  ]
+]