From 82be0eb30df9c7d10749f4f75cd13a50437781a3 Mon Sep 17 00:00:00 2001
From: Abigail <abigail@abigail.be>
Date: Mon, 25 Oct 2021 18:13:13 +0200
Subject: Lua solutions for week 136

---
 challenge-136/abigail/README.md    |  2 ++
 challenge-136/abigail/lua/ch-1.lua | 42 ++++++++++++++++++++++++++++++++++++++
 challenge-136/abigail/lua/ch-2.lua | 20 ++++++++++++++++++
 3 files changed, 64 insertions(+)
 create mode 100644 challenge-136/abigail/lua/ch-1.lua
 create mode 100644 challenge-136/abigail/lua/ch-2.lua

diff --git a/challenge-136/abigail/README.md b/challenge-136/abigail/README.md
index 6019a49bff..436e6a57e4 100644
--- a/challenge-136/abigail/README.md
+++ b/challenge-136/abigail/README.md
@@ -5,10 +5,12 @@
 * [GNU AWK](awk/ch-1.gawk)
 * [Bash](bash/ch-1.sh)
 * [C](c/ch-1.c)
+* [Lua](lua/ch-1.lua)
 * [Perl](perl/ch-1.pl)
 
 ## Part 2
 
 * [AWK](awk/ch-2.awk)
 * [C](c/ch-2.c)
+* [Lua](lua/ch-2.lua)
 * [Perl](perl/ch-2.pl)
diff --git a/challenge-136/abigail/lua/ch-1.lua b/challenge-136/abigail/lua/ch-1.lua
new file mode 100644
index 0000000000..182d18fba7
--- /dev/null
+++ b/challenge-136/abigail/lua/ch-1.lua
@@ -0,0 +1,42 @@
+#!/opt/local/bin/lua
+
+--
+-- See ../README.md
+--
+
+--
+-- Run as: lua ch-1.lua < input-file
+--
+
+--
+-- Find the GCD, using Euclids algorithm
+--    (https://en.wikipedia.org/wiki/Euclidean_algorithm#Implementations)
+--
+function gcd (a, b)
+    while b > 0 do
+        a, b = b, a % b
+    end
+    return a
+end
+
+--
+-- Precalculate all the relevant powers of 2. Note that in pre 5-3 lua
+-- integers are doubles, and start losing precision at 2^53, so we go
+-- up to 2^52.
+--
+local power_of_2 = {}
+local power      = 1
+for i = 1, 52 do
+    power = power * 2
+    power_of_2 [power] = 1
+end
+
+
+for line in io . lines () do
+    local _, _, n, m = line : find ("([0-9]+)%s+([0-9]+)")
+    if power_of_2 [gcd (tonumber (n), tonumber (m))] then
+        print (1)
+    else
+        print (0)
+    end
+end
diff --git a/challenge-136/abigail/lua/ch-2.lua b/challenge-136/abigail/lua/ch-2.lua
new file mode 100644
index 0000000000..d403ce64d6
--- /dev/null
+++ b/challenge-136/abigail/lua/ch-2.lua
@@ -0,0 +1,20 @@
+#!/opt/local/bin/lua
+
+--
+-- See ../README.md
+--
+
+--
+-- Run as: lua ch-2.lua < input-file
+--
+
+function count (target, this_fib, prev_fib)
+    if target <  this_fib then return 0 end
+    if target == this_fib then return 1 end
+    return (count (target - this_fib, this_fib + prev_fib, this_fib) +
+            count (target,            this_fib + prev_fib, this_fib))
+end
+
+for line in io . lines () do
+    print (count (tonumber (line), 1, 1))
+end
-- 
cgit