From c5d7bbdf41bd9632858245f3afd93319186a14d9 Mon Sep 17 00:00:00 2001
From: Roger Bell_West <roger@firedrake.org>
Date: Mon, 14 Nov 2022 09:33:51 +0000
Subject: Solutions for challenge #191

---
 challenge-191/roger-bell-west/lua/ch-2.lua | 73 ++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100755 challenge-191/roger-bell-west/lua/ch-2.lua

(limited to 'challenge-191/roger-bell-west/lua/ch-2.lua')

diff --git a/challenge-191/roger-bell-west/lua/ch-2.lua b/challenge-191/roger-bell-west/lua/ch-2.lua
new file mode 100755
index 0000000000..f05338a714
--- /dev/null
+++ b/challenge-191/roger-bell-west/lua/ch-2.lua
@@ -0,0 +1,73 @@
+#! /usr/bin/lua
+
+function cutelist(n)
+   local tab = {}
+   local tmp = {}
+   for x = 1,n do
+      local row = {}
+      for y = 1,n do
+         table.insert(row, false)
+      end
+      table.insert(tab, row)
+      table.insert(tmp, x)
+   end
+   for x = 1,n do
+      for y = 1,x do
+         if x % y ~= 0 and y % x ~= 0 then
+            tab[x][y] = true
+            tab[y][x] = true
+         end
+      end
+   end
+   local count = 0
+   local stackl = {{}}
+   local stackc = {tmp}
+   while #stackl > 0 do
+      local l = table.remove(stackl)
+      local c = table.remove(stackc)
+      if #c == 0 and #l == n then
+         count = count + 1
+      else
+         local place = #l + 1
+         for i, candidate in ipairs(c) do
+            if not tab[place][candidate] then
+               local ql = {}
+               for j, qx in ipairs(l) do
+                  table.insert(ql, qx)
+               end
+               table.insert(ql, candidate)
+               table.insert(stackl, ql)
+               local qc = {}
+               for j, qx in ipairs(c) do
+                  if qx ~= candidate then
+                     table.insert(qc, qx)
+                  end
+               end
+               table.insert(stackc, qc)
+            end
+         end
+      end
+   end
+   return count
+end
+
+if cutelist(2) == 2 then
+   io.write("Pass")
+else
+   io.write("FAIL")
+end
+io.write(" ")
+
+if cutelist(10) == 700 then
+   io.write("Pass")
+else
+   io.write("FAIL")
+end
+io.write(" ")
+
+if cutelist(15) == 24679 then
+   io.write("Pass")
+else
+   io.write("FAIL")
+end
+print("")
-- 
cgit