1 files changed, 155 insertions, 0 deletions
diff --git a/challenge-220/roger-bell-west/lua/ch-2.lua b/challenge-220/roger-bell-west/lua/ch-2.lua
new file mode 100755
index 0000000000..57254c3a40
--- /dev/null
+++ b/challenge-220/roger-bell-west/lua/ch-2.lua
@@ -0,0 +1,155 @@
+#! /usr/bin/lua
+
+-- by Michael Anderson at
+-- https://stackoverflow.com/questions/8722620/comparing-two-index-tables-by-index-value-in-lua
+-- modified by Roger
+function recursive_compare(t1,t2)
+  -- Use usual comparison first.
+  if t1==t2 then return true end
+  -- We only support non-default behavior for tables
+  if (type(t1)~="table") then return false end
+  -- They better have the same metatables
+  local mt1 = getmetatable(t1)
+  local mt2 = getmetatable(t2)
+  if( not recursive_compare(mt1,mt2) ) then return false end
+  -- Build list of all keys
+  local kk = {}
+  for k1, _ in pairs(t1) do
+     kk[k1] = true
+  end
+  for k2, _ in pairs(t2) do
+     kk[k2] = true
+  end
+  -- Check each key that exists in at least one table
+  for k, _ in pairs(kk) do
+     if (not recursive_compare(t1[k], t2[k])) then
+        return false
+     end
+  end
+  return true
+end
+
+function keys(t)
+   local a = {}
+   for k, v in pairs(t) do
+      table.insert(a, k)
+   end
+   return a
+end
+
+function deepcopy(src)
+   local dst = {}
+   for k, v in pairs(src) do
+      if type(v) == "table" then
+         v = deepcopy(v)
+      end
+      dst[k] = v
+   end
+   return dst
+end
+
+function permute(a)
+   local out = {}
+   local n = #a
+   local c = {}
+   for i = 1,n do
+      table.insert(c, 1)
+   end
+   table.insert(out, deepcopy(a))
+   local i=1
+   while true do
+      if i > n then
+         break
+      end
+      if c[i] < i then
+         if i % 2 == 1 then
+            a[1],a[i] = a[i],a[1]
+         else
+            a[c[i]],a[i] = a[i],a[c[i]]
+         end
+         table.insert(out, deepcopy(a))
+         c[i] = c[i]+1
+         i = 1
+      else
+         c[i] = 1
+         i = i+1
+      end
+   end
+   return out
+end
+
+function propersize(t)
+   local l=0
+   for k,v in pairs(t) do
+      l = l + 1
+   end
+   return l
+end
+
+function squared(a)
+   return a * a
+end
+
+function encode(sq, base)
+   local a = 0
+   for _, v in ipairs(sq) do
+      a = a * base
+      a = a + v
+   end
+   return a
+end
+
+function decode(a, base)
+   local eq = {}
+   while a > 0 do
+      table.insert(eq, 1, a % base)
+      a = a // base
+   end
+   return eq
+end
+
+function squareful(lst)
+   local results = {}
+   local squares = {}
+   local base = math.max(table.unpack(lst)) + 1
+   for _, la in ipairs(permute(lst)) do
+      local squareful = true
+      for i = 1, #la-1 do
+         local cs = la[i] + la[i + 1]
+         local mx = squared(propersize(squares))
+         while cs > mx do
+            mx = squared(propersize(squares) + 1)
+            squares[mx] = true
+         end
+         if squares[cs] == nil then
+            squareful = false
+            break
+         end
+      end
+      if squareful then
+         results[encode(la, base)] = true
+      end
+   end
+   local o = keys(results)
+   table.sort(o)
+   local out = {}
+   for _, v in ipairs(o) do
+      table.insert(out, decode(v, base))
+   end
+   return out
+end
+
+if recursive_compare(squareful({1, 17, 8}), {{1, 8, 17}, {17, 8, 1}}) then
+  io.write("Pass")
+else
+  io.write("FAIL")
+end
+io.write(" ")
+
+if recursive_compare(squareful({2, 2, 2}), {{2, 2, 2}}) then
+  io.write("Pass")
+else
+  io.write("FAIL")
+end
+print("")
+