#! /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("")