Attempt p3 in lua

README.rst

@@ -93,7 +93,7 @@ Olivia's Project Euler Solutions
    |            | Browser [#]_               |        | |CodeQL| |br|     |
    |            |                            |        | |ESLint|          |
    +------------+----------------------------+--------+-------------------+
-   | Lua        | Lua 5+ [#]_                | 11     | |Luai| |br|       |
+   | Lua        | Lua 5+ [#]_                | 12     | |Luai| |br|       |
    |            |                            |        | |LuaCheck|        |
    +------------+----------------------------+--------+-------------------+
    | Python     | CPython 3.6+ |br|          | 80     | |Python| |br|     |

docs/index.rst

@@ -81,7 +81,7 @@ Problems Solved
   +-----------+-----------+------------+------------+------------+------------+------------+------------+------------+
   |:prob:`002`|:c-d:`0002`|:cp-d:`0002`|:cs-d:`0002`|:ja-d:`0002`|:js-d:`0002`|:lu-d:`0002`|:py-d:`0002`|:rs-d:`0002`|
   +-----------+-----------+------------+------------+------------+------------+------------+------------+------------+
-  |:prob:`003`|:c-d:`0003`|:cp-d:`0003`|:cs-d:`0003`|            |:js-d:`0003`|            |:py-d:`0003`|:rs-d:`0003`|
+  |:prob:`003`|:c-d:`0003`|:cp-d:`0003`|:cs-d:`0003`|            |:js-d:`0003`|:lu-d:`0003`|:py-d:`0003`|:rs-d:`0003`|
   +-----------+-----------+------------+------------+------------+------------+------------+------------+------------+
   |:prob:`004`|:c-d:`0004`|:cp-d:`0004`|:cs-d:`0004`|:ja-d:`0004`|:js-d:`0004`|:lu-d:`0004`|:py-d:`0004`|:rs-d:`0004`|
   +-----------+-----------+------------+------------+------------+------------+------------+------------+------------+

docs/src/lua/lib/primes.rst

@@ -0,0 +1,20 @@
+primes.lua
+=========
+
+View source code :source:`lua/src/lib/primes.lua`
+
+This module directly ports some of the logic found in Python's :external:py:obj:`primes`.
+
+.. lua:function:: prime(stop)
+
+    :return: An iterator over the prime numbers, optionally up to ``stop``
+    :rtype: table
+
+.. lua:function:: primes_factors(n)
+
+    :return: An iterator over the prime factors of ``n``
+    :rtype: table
+
+.. literalinclude:: ../../../../lua/src/lib/primes.lua
+   :language: Lua
+   :linenos:

docs/src/lua/p0003.rst

@@ -0,0 +1,23 @@
+Lua Implementation of Problem 3
+===============================
+
+View source code :source:`lua/src/p0003.lua`
+
+Includes
+--------
+
+- `primes.lua <./lib/primes.html>`__
+
+Solution
+--------
+
+.. lua:function:: solution()
+
+    :return: The solution to problem 3
+    :rtype: number
+
+.. literalinclude:: ../../../lua/src/p0003.lua
+   :language: Lua
+   :linenos:
+
+.. tags:: factorization, prime-number, lua-iterator

lua/README.rst

@@ -57,6 +57,7 @@ Problems Solved
 
 -  ☒ `1 <./src/p0001.lua>`__
 -  ☒ `2 <./src/p0002.lua>`__
+-  ☒ `3 <./src/p0003.lua>`__
 -  ☒ `4 <./src/p0004.lua>`__
 -  ☒ `6 <./src/p0006.lua>`__
 -  ☒ `8 <./src/p0008.lua>`__

lua/src/lib/math.lua

@@ -1,5 +1,3 @@
--- This file is a direct port of Python's range functions
-
 local function factorial(n)
     local answer = 1
 

lua/src/lib/primes.lua

@@ -0,0 +1,66 @@
+local function primes(stop)
+    local p = 2
+    local known_primes = {}
+
+    local function next()
+        if p == 2
+        do
+            p = 3
+            known_primes[0] = 2
+            return 2
+        end
+
+        while stop == nil or p < stop
+        do
+            local broken = false
+            for i = 1,#known_primes,1
+            do
+                if p % known_primes[0] ~= 0
+                then
+                    broken = true
+                    break
+                end
+            end
+
+            p = p + 2
+            if not broken
+            then
+                known_primes[#known_primes + 1] = p - 2
+                return p - 2
+            end
+        end
+    end
+
+    return {
+        next = next,
+    }
+end
+
+local function prime_factors(n)
+    local pgen = primes()
+    local p = pgen.next()
+
+    local function next()
+        while p ~= nil and n % p != 0
+        do
+            p = pgen.next()
+        end
+
+        if p == nil
+        then
+            return nil
+        end
+
+        n = n / p
+        return p
+    end
+
+    return {
+        next = next,
+    }
+end
+
+return {
+    primes = primes,
+    prime_factors = prime_factors,
+}

lua/src/p0003.lua

@@ -0,0 +1,22 @@
+-- Project Euler Problem 3
+--
+-- Problem:
+--
+-- The prime factors of 13195 are 5, 7, 13 and 29.
+--
+-- What is the largest prime factor of the number 600851475143 ?
+
+return {
+    solution = function()
+        local fgen = prime_factors(600851475143)
+        local f = 0
+        local answer = 0
+
+        while (f = fgen.next()) ~= nil
+        do
+            answer = f
+        end
+
+        return answer
+    end
+}

lua/test.lua

@@ -47,6 +47,7 @@ end
 local problems = {
     ["p0001.lua"] = {233168, false},
     ["p0002.lua"] = {4613732, false},
+    ["p0003.lua"] = {6857, false},
     ["p0004.lua"] = {906609, false},
     ["p0006.lua"] = {25164150, false},
     ["p0008.lua"] = {23514624000, false},