1 files changed, 61 insertions, 0 deletions
diff --git a/challenge-245/roger-bell-west/lua/ch-2.lua b/challenge-245/roger-bell-west/lua/ch-2.lua
new file mode 100755
index 0000000000..063ad63ad8
--- /dev/null
+++ b/challenge-245/roger-bell-west/lua/ch-2.lua
@@ -0,0 +1,61 @@
+#! /usr/bin/lua
+
+function combinations(arr, k)
+   local c = {}
+   for i = 1, k do
+      table.insert(c, i)
+   end
+   table.insert(c, #arr + 1)
+   table.insert(c, 0)
+   local out = {}
+   while true do
+      local inner = {}
+      for i = k, 1, -1 do
+         table.insert(inner, arr[c[i]])
+      end
+      table.insert(out, inner)
+      local j = 1
+      while c[j] + 1 == c[j + 1] do
+         c[j] = j
+         j = j + 1
+      end
+      if j > k then
+         break
+      end
+      c[j] = c[j] + 1
+   end
+   return ipairs(out)
+end
+
+function largestofthree(digits)
+   ordered = digits
+   table.sort(ordered, function (i,j) return i < j end)
+   local mx = 0
+   for n = #ordered, 1, -1 do
+      for _a, c in combinations(ordered, n) do
+         local t = 0
+         for _b, d in ipairs(c) do
+            t = t * 10 + d
+         end
+         if t > mx and t % 3 == 0 then
+            mx = t
+         end
+      end
+   end
+   return mx
+end
+
+if largestofthree({8, 1, 9}) == 981 then
+  io.write("Pass")
+else
+  io.write("FAIL")
+end
+io.write(" ")
+
+if largestofthree({8, 6, 7, 1, 0}) == 8760 then
+  io.write("Pass")
+else
+  io.write("FAIL")
+end
+print("")
+