2 files changed, 139 insertions, 0 deletions
diff --git a/challenge-147/roger-bell-west/lua/ch-1.lua b/challenge-147/roger-bell-west/lua/ch-1.lua
new file mode 100755
index 0000000000..c2e65f23b0
--- /dev/null
+++ b/challenge-147/roger-bell-west/lua/ch-1.lua
@@ -0,0 +1,101 @@
+#! /usr/bin/lua
+
+-- by Michael Anderson at
+-- https://stackoverflow.com/questions/8722620/comparing-two-index-tables-by-index-value-in-lua
+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
+
+  -- Check each key-value pair
+  -- We have to do this both ways in case we miss some.
+  -- TODO: Could probably be smarter and not check those we've 
+  -- already checked though!
+  for k1,v1 in pairs(t1) do
+    local v2 = t2[k1]
+    if( not recursive_compare(v1,v2) ) then return false end
+  end
+  for k2,v2 in pairs(t2) do
+    local v1 = t1[k2]
+    if( not recursive_compare(v1,v2) ) then return false end
+  end
+
+  return true  
+end
+
+function genprimes(mx)
+   local primesh = {}
+   for i = 2, 3 do
+      primesh[i] = true
+   end
+   for i = 6, mx+1, 6 do
+      for j = i-1, i+1, 2 do
+         if j <= mx then
+            primesh[j]=true
+         end
+      end
+   end
+   local q={2,3,5,7}
+   local p=table.remove(q,1)
+   local mr=math.floor(math.sqrt(mx))
+   while p <= mr do
+      if primesh[p] ~= nil then
+         for i = p*p,mx,p do
+            primesh[i] = nil
+         end
+      end
+      if #q < 2 then
+         table.insert(q,q[#q]+4)
+         table.insert(q,q[#q]+2)
+      end
+      p=table.remove(q,1)
+   end
+   local primes = {}
+   for k,v in pairs(primesh) do
+      table.insert(primes,k)
+   end
+   table.sort(primes)
+   return primes
+end
+
+function ltruncprimes(count)
+   out={}
+   lt=0
+   p={}
+   pp={}
+   for i,v in ipairs(genprimes(500)) do
+      s=tostring(v)
+      table.insert(p,s)
+      pp[s]=true
+   end
+   for j,pc in ipairs(p) do
+      l=#pc
+      c=true
+      for i = 2,l do
+         if pp[string.sub(pc,i)] == nil then
+            c=false
+            break
+         end
+      end
+      if c then
+         table.insert(out,tonumber(pc))
+         lt = lt + 1
+         if lt >= count then
+            break
+         end
+      end
+   end
+   return out
+end
+
+if recursive_compare(ltruncprimes(20),{2, 3, 5, 7, 13, 17, 23, 37, 43, 47, 53, 67, 73, 83, 97, 113, 137, 167, 173, 197}) then
+   io.write("Pass")
+else
+   io.write("FAIL")
+end
+print("")
diff --git a/challenge-147/roger-bell-west/lua/ch-2.lua b/challenge-147/roger-bell-west/lua/ch-2.lua
new file mode 100755
index 0000000000..cbe31d0ed8
--- /dev/null
+++ b/challenge-147/roger-bell-west/lua/ch-2.lua
@@ -0,0 +1,38 @@
+#! /usr/bin/lua
+
+function pentagon(n)
+   return math.floor(n*(3*n-1)/2)
+end
+
+function pentpair()
+   fpent={}
+   rpent={}
+   mx=0
+   a=1
+   while 1 do
+      while mx < a do
+         mx = mx + 1
+         table.insert(fpent,pentagon(mx))
+         rpent[fpent[mx]]=mx
+      end
+      for b = 1,a do
+         d=fpent[a]-fpent[b]
+         if rpent[d] ~= nil then
+            s=fpent[a]+fpent[b]
+            while s > fpent[mx] do
+               mx = mx + 1
+               table.insert(fpent,pentagon(mx))
+               rpent[fpent[mx]]=mx
+            end
+            if rpent[s] ~= nil then
+               print(string.format("P(%d) + P(%d) = %d + %d = %d = P(%d)",a,b,fpent[a],fpent[b],s,rpent[s]))
+               print(string.format("P(%d) - P(%d) = %d - %d = %d = P(%d)",a,b,fpent[a],fpent[b],d,rpent[d]))
+               os.exit(0)
+            end
+         end
+      end
+      a = a + 1
+   end
+end
+
+pentpair()