Initial upload

julia/prime-factors/.exercism/metadata.json

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+{"track":"julia","exercise":"prime-factors","id":"5198169256b2415da05999facf51ba03","url":"https://exercism.io/my/solutions/5198169256b2415da05999facf51ba03","handle":"halfdan","is_requester":true,"auto_approve":false}

julia/prime-factors/README.md

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+# Prime Factors
+
+Compute the prime factors of a given natural number.
+
+A prime number is only evenly divisible by itself and 1.
+
+Note that 1 is not a prime number.
+
+## Example
+
+What are the prime factors of 60?
+
+- Our first divisor is 2. 2 goes into 60, leaving 30.
+- 2 goes into 30, leaving 15.
+  - 2 doesn't go cleanly into 15. So let's move on to our next divisor, 3.
+- 3 goes cleanly into 15, leaving 5.
+  - 3 does not go cleanly into 5. The next possible factor is 4.
+  - 4 does not go cleanly into 5. The next possible factor is 5.
+- 5 does go cleanly into 5.
+- We're left only with 1, so now, we're done.
+
+Our successful divisors in that computation represent the list of prime
+factors of 60: 2, 2, 3, and 5.
+
+You can check this yourself:
+
+- 2 * 2 * 3 * 5
+- = 4 * 15
+- = 60
+- Success!
+
+## Source
+
+The Prime Factors Kata by Uncle Bob [http://butunclebob.com/ArticleS.UncleBob.ThePrimeFactorsKata](http://butunclebob.com/ArticleS.UncleBob.ThePrimeFactorsKata)
+
+## Version compatibility
+This exercise has been tested on Julia versions >=1.0.
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

julia/prime-factors/prime-factors.ipynb

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+{
+    "cells": [
+        {
+            "cell_type": "markdown",
+            "metadata": {},
+            "source": ["# Prime Factors\n", "\n", "Compute the prime factors of a given natural number.\n", "\n", "A prime number is only evenly divisible by itself and 1.\n", "\n", "Note that 1 is not a prime number.\n", "\n", "## Example\n", "\n", "What are the prime factors of 60?\n", "\n", "- Our first divisor is 2. 2 goes into 60, leaving 30.\n", "- 2 goes into 30, leaving 15.\n", "  - 2 doesn't go cleanly into 15. So let's move on to our next divisor, 3.\n", "- 3 goes cleanly into 15, leaving 5.\n", "  - 3 does not go cleanly into 5. The next possible factor is 4.\n", "  - 4 does not go cleanly into 5. The next possible factor is 5.\n", "- 5 does go cleanly into 5.\n", "- We're left only with 1, so now, we're done.\n", "\n", "Our successful divisors in that computation represent the list of prime\n", "factors of 60: 2, 2, 3, and 5.\n", "\n", "You can check this yourself:\n", "\n", "- 2 * 2 * 3 * 5\n", "- = 4 * 15\n", "- = 60\n", "- Success!\n", "\n", "## Source\n", "\n", "The Prime Factors Kata by Uncle Bob [http://butunclebob.com/ArticleS.UncleBob.ThePrimeFactorsKata](http://butunclebob.com/ArticleS.UncleBob.ThePrimeFactorsKata)\n", "\n", "## Version compatibility\n", "This exercise has been tested on Julia versions >=1.0.\n", "\n", "## Submitting Incomplete Solutions\n", "It's possible to submit an incomplete solution so you can see how others have completed the exercise."]
+        },
+        {
+            "cell_type": "markdown",
+            "metadata": {},
+            "source": ["## Your solution"]
+        },
+        {
+            "cell_type": "code",
+            "execution_count": null,
+            "metadata": {},
+            "outputs": [],
+            "source": ["# submit\n", ""]
+        },
+        {
+            "cell_type": "markdown",
+            "metadata": {},
+            "source": ["## Test suite"]
+        },
+        {
+            "cell_type": "code",
+            "execution_count": null,
+            "metadata": {},
+            "outputs": [],
+            "source": ["# include(\"prime-factors.jl\")\n", "using Test\n", "\n", "@testset \"no factors\" begin\n", "    @test prime_factors(1) == []\n", "end\n", "\n", "@testset \"prime number\" begin\n", "    @test prime_factors(2) == [2]\n", "end\n", "\n", "@testset \"square of a prime\" begin\n", "    @test prime_factors(9) == [3, 3]\n", "end\n", "\n", "@testset \"cube of a prime\" begin\n", "    @test prime_factors(8) == [2, 2, 2]\n", "end\n", "\n", "@testset \"product of primes and non-primes\" begin\n", "    @test prime_factors(12) == [2, 2, 3]\n", "end\n", "\n", "@testset \"product of primes\" begin\n", "    @test prime_factors(901255) == [5, 17, 23, 461]\n", "end\n", "\n", "@testset \"factors include a large prime\" begin\n", "    @test prime_factors(93819012551) == [11, 9539, 894119]\n", "end"]
+        },
+        {
+            "cell_type": "markdown",
+            "metadata": {},
+            "source": [
+                "## Prepare submission\n",
+                "To submit your exercise, you need to save your solution in a file called `prime-factors.jl` before using the CLI.\n",
+                "You can either create it manually or use the following functions, which will automatically write every notebook cell that starts with `# submit` to the file `prime-factors.jl`.\n"
+            ]
+        },
+        {
+            "cell_type": "code",
+            "execution_count": null,
+            "metadata": {},
+            "outputs": [],
+            "source": [
+                "# using Pkg; Pkg.add(\"Exercism\")\n",
+                "# using Exercism\n",
+                "# Exercism.create_submission(\"prime-factors\")"
+            ]
+        }
+    ],
+    "metadata": {
+        "kernelspec": {
+            "display_name": "Julia 1.3.0",
+            "language": "julia",
+            "name": "julia-1.3"
+        },
+        "language_info": {
+            "file_extension": ".jl",
+            "mimetype": "application/julia",
+            "name": "julia",
+            "version": "1.3.0"
+        }
+    },
+    "nbformat": 4,
+    "nbformat_minor": 2
+}

julia/prime-factors/prime-factors.jl

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+function prime_factors(n::Int)
+    primes = []
+    while n != 1 && n > 1
+        for i in 2:n
+            if n % i == 0
+                push!(primes, i)
+                n = div(n, i)
+                break
+            end
+        end
+    end
+    primes
+end

julia/prime-factors/runtests.jl

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+include("prime-factors.jl")
+using Test
+
+@testset "no factors" begin
+    @test prime_factors(1) == []
+end
+
+@testset "prime number" begin
+    @test prime_factors(2) == [2]
+end
+
+@testset "square of a prime" begin
+    @test prime_factors(9) == [3, 3]
+end
+
+@testset "cube of a prime" begin
+    @test prime_factors(8) == [2, 2, 2]
+end
+
+@testset "product of primes and non-primes" begin
+    @test prime_factors(12) == [2, 2, 3]
+end
+
+@testset "product of primes" begin
+    @test prime_factors(901255) == [5, 17, 23, 461]
+end
+
+@testset "factors include a large prime" begin
+    @test prime_factors(93819012551) == [11, 9539, 894119]
+end