From 44bcd3ae0c35b887bd579e60c17198360f3497c3 Mon Sep 17 00:00:00 2001
From: Abigail <abigail@abigail.be>
Date: Tue, 30 Nov 2021 20:04:35 +0100
Subject: Solutions week 141

---
 challenge-141/abigail/lua/ch-2.lua | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 challenge-141/abigail/lua/ch-2.lua

(limited to 'challenge-141/abigail/lua/ch-2.lua')

diff --git a/challenge-141/abigail/lua/ch-2.lua b/challenge-141/abigail/lua/ch-2.lua
new file mode 100644
index 0000000000..b7f87027f4
--- /dev/null
+++ b/challenge-141/abigail/lua/ch-2.lua
@@ -0,0 +1,37 @@
+#!/opt/local/bin/lua
+
+--
+-- See ../README.md
+--
+
+--
+-- Run as: lua ch-2.lua < input-file
+--
+
+function substrings (n, m, prefix, max)
+    if n : len () == 0 then
+        if prefix > -1 and prefix < max and prefix % m == 0 then
+            return 1
+        else
+            return 0
+        end
+    end
+
+    local fc   = tonumber (n : sub (1, 1))
+    local tail = n : sub (2)
+    local n_prefix
+    if prefix == -1 then
+        n_prefix = fc
+    else
+        n_prefix = 10 * prefix + fc
+    end
+
+    return substrings (tail, m, n_prefix, max) +
+           substrings (tail, m,   prefix, max)
+end
+
+
+for line in io . lines () do
+    local _, _, n, m = line : find ("([0-9]+)%s+([0-9]+)")
+    print (substrings (n, tonumber (m), -1, tonumber (n)))
+end
-- 
cgit