diff --git a/config.json b/config.json index 7ed89e4..8932b17 100644 --- a/config.json +++ b/config.json @@ -117,6 +117,14 @@ "practices": [], "prerequisites": [], "difficulty": 6 + }, + { + "slug": "collatz-conjecture", + "name": "Collatz Conjecture", + "uuid": "dc42f98e-d0fe-4c0f-ab4d-1954cf839ea8", + "practices": [], + "prerequisites": [], + "difficulty": 2 } ] }, diff --git a/exercises/practice/collatz-conjecture/.docs/instructions.md b/exercises/practice/collatz-conjecture/.docs/instructions.md new file mode 100644 index 0000000..af332a8 --- /dev/null +++ b/exercises/practice/collatz-conjecture/.docs/instructions.md @@ -0,0 +1,3 @@ +# Instructions + +Given a positive integer, return the number of steps it takes to reach 1 according to the rules of the Collatz Conjecture. diff --git a/exercises/practice/collatz-conjecture/.docs/introduction.md b/exercises/practice/collatz-conjecture/.docs/introduction.md new file mode 100644 index 0000000..c35bdeb --- /dev/null +++ b/exercises/practice/collatz-conjecture/.docs/introduction.md @@ -0,0 +1,28 @@ +# Introduction + +One evening, you stumbled upon an old notebook filled with cryptic scribbles, as though someone had been obsessively chasing an idea. +On one page, a single question stood out: **Can every number find its way to 1?** +It was tied to something called the **Collatz Conjecture**, a puzzle that has baffled thinkers for decades. + +The rules were deceptively simple. +Pick any positive integer. + +- If it's even, divide it by 2. +- If it's odd, multiply it by 3 and add 1. + +Then, repeat these steps with the result, continuing indefinitely. + +Curious, you picked number 12 to test and began the journey: + +12 ➜ 6 ➜ 3 ➜ 10 ➜ 5 ➜ 16 ➜ 8 ➜ 4 ➜ 2 ➜ 1 + +Counting from the second number (6), it took 9 steps to reach 1, and each time the rules repeated, the number kept changing. +At first, the sequence seemed unpredictable — jumping up, down, and all over. +Yet, the conjecture claims that no matter the starting number, we'll always end at 1. + +It was fascinating, but also puzzling. +Why does this always seem to work? +Could there be a number where the process breaks down, looping forever or escaping into infinity? +The notebook suggested solving this could reveal something profound — and with it, fame, [fortune][collatz-prize], and a place in history awaits whoever could unlock its secrets. + +[collatz-prize]: https://mathprize.net/posts/collatz-conjecture/ diff --git a/exercises/practice/collatz-conjecture/.meta/config.json b/exercises/practice/collatz-conjecture/.meta/config.json new file mode 100644 index 0000000..1b6fb58 --- /dev/null +++ b/exercises/practice/collatz-conjecture/.meta/config.json @@ -0,0 +1,19 @@ +{ + "authors": [ + "quintuple-mallard" + ], + "files": { + "solution": [ + "collatz-conjecture.nu" + ], + "test": [ + "tests.nu" + ], + "example": [ + ".meta/example.nu" + ] + }, + "blurb": "Calculate the number of steps to reach 1 using the Collatz conjecture.", + "source": "Wikipedia", + "source_url": "https://en.wikipedia.org/wiki/Collatz_conjecture" +} diff --git a/exercises/practice/collatz-conjecture/.meta/example.nu b/exercises/practice/collatz-conjecture/.meta/example.nu new file mode 100644 index 0000000..f9c1887 --- /dev/null +++ b/exercises/practice/collatz-conjecture/.meta/example.nu @@ -0,0 +1,17 @@ +export def steps [number] { + if $number <= 0 { + error make {msg: "Only positive integers are allowed"} + } + mut number = $number + mut steps = 0 + while $number != 1 { + $steps += 1 + if ($number mod 2) == 1 { + $number *= 3 + $number += 1 + } else { + $number /= 2 + } + } + $steps +} diff --git a/exercises/practice/collatz-conjecture/.meta/tests.toml b/exercises/practice/collatz-conjecture/.meta/tests.toml new file mode 100644 index 0000000..cc34e16 --- /dev/null +++ b/exercises/practice/collatz-conjecture/.meta/tests.toml @@ -0,0 +1,38 @@ +# 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. + +[540a3d51-e7a6-47a5-92a3-4ad1838f0bfd] +description = "zero steps for one" + +[3d76a0a6-ea84-444a-821a-f7857c2c1859] +description = "divide if even" + +[754dea81-123c-429e-b8bc-db20b05a87b9] +description = "even and odd steps" + +[ecfd0210-6f85-44f6-8280-f65534892ff6] +description = "large number of even and odd steps" + +[7d4750e6-def9-4b86-aec7-9f7eb44f95a3] +description = "zero is an error" +include = false + +[2187673d-77d6-4543-975e-66df6c50e2da] +description = "zero is an error" +reimplements = "7d4750e6-def9-4b86-aec7-9f7eb44f95a3" + +[c6c795bf-a288-45e9-86a1-841359ad426d] +description = "negative value is an error" +include = false + +[ec11f479-56bc-47fd-a434-bcd7a31a7a2e] +description = "negative value is an error" +reimplements = "c6c795bf-a288-45e9-86a1-841359ad426d" diff --git a/exercises/practice/collatz-conjecture/collatz-conjecture.nu b/exercises/practice/collatz-conjecture/collatz-conjecture.nu new file mode 100644 index 0000000..86b2f77 --- /dev/null +++ b/exercises/practice/collatz-conjecture/collatz-conjecture.nu @@ -0,0 +1,3 @@ +export def steps [number] { + error make {msg: "Please implement steps"} +} diff --git a/exercises/practice/collatz-conjecture/tests.nu b/exercises/practice/collatz-conjecture/tests.nu new file mode 100644 index 0000000..a986b00 --- /dev/null +++ b/exercises/practice/collatz-conjecture/tests.nu @@ -0,0 +1,18 @@ +use collatz-conjecture.nu steps +use std/assert +# zero steps for one +assert equal (steps 1) 0 +# divide if even +assert equal (steps 16) 4 +# even and odd steps +assert equal (steps 12) 9 +# large number of even and odd steps +assert equal (steps 1000000) 152 +# zero is an error +assert equal (try { steps 0 } catch {|e| + $e.msg +}) "Only positive integers are allowed" +# negative value is an error +assert equal (try { steps (-15) } catch {|e| + $e.msg +}) "Only positive integers are allowed" diff --git a/exercises/practice/resistor-color-duo/.meta/config.json b/exercises/practice/resistor-color-duo/.meta/config.json index 04c0bd5..7b53b87 100644 --- a/exercises/practice/resistor-color-duo/.meta/config.json +++ b/exercises/practice/resistor-color-duo/.meta/config.json @@ -15,6 +15,5 @@ }, "blurb": "Convert color codes, as used on resistors, to a numeric value.", "source": "Maud de Vries, Erik Schierboom", - "source_url": "https://github.com/exercism/problem-specifications/issues/1464", - "difficulty": 2 + "source_url": "https://github.com/exercism/problem-specifications/issues/1464" } diff --git a/exercises/practice/resistor-color-trio/.meta/config.json b/exercises/practice/resistor-color-trio/.meta/config.json index 44143a1..53e3554 100644 --- a/exercises/practice/resistor-color-trio/.meta/config.json +++ b/exercises/practice/resistor-color-trio/.meta/config.json @@ -15,6 +15,5 @@ }, "blurb": "Convert color codes, as used on resistors, to a human-readable label.", "source": "Maud de Vries, Erik Schierboom", - "source_url": "https://github.com/exercism/problem-specifications/issues/1549", - "difficulty": 4 + "source_url": "https://github.com/exercism/problem-specifications/issues/1549" } diff --git a/exercises/practice/resistor-color/.meta/config.json b/exercises/practice/resistor-color/.meta/config.json index 914c584..db31a4a 100644 --- a/exercises/practice/resistor-color/.meta/config.json +++ b/exercises/practice/resistor-color/.meta/config.json @@ -15,6 +15,5 @@ }, "blurb": "Convert a resistor band's color to its numeric representation.", "source": "Maud de Vries, Erik Schierboom", - "source_url": "https://github.com/exercism/problem-specifications/issues/1458", - "difficulty": 1 + "source_url": "https://github.com/exercism/problem-specifications/issues/1458" } diff --git a/exercises/practice/strain/.meta/config.json b/exercises/practice/strain/.meta/config.json index 9f3cf35..55616ed 100644 --- a/exercises/practice/strain/.meta/config.json +++ b/exercises/practice/strain/.meta/config.json @@ -15,6 +15,5 @@ }, "blurb": "Implement the `keep` and `discard` operation on collections.", "source": "Conversation with James Edward Gray II", - "source_url": "http://graysoftinc.com/", - "difficulty": 2 + "source_url": "http://graysoftinc.com/" }