从Lua中的表中减去表

这似乎有效,但有更有效的方法吗？

function array_sub(t1, t2)

-- Substract Arrays from Array 
-- Usage: nretable =  array_sub(T1, T2)  -- removes T1 from T2

 table.sort( t1 )

for i = 1, #t2 do
    if (t2[i] ~= nil) then
      for j = 1, #t1 do
        if (t2[i] == t1 [j]) then
        table.remove (t2, i)
        end
      end
    end
end
    return t2
end


local remove ={1,2,3} 
local full = {}; for i = 1, 10 do full[i] = i end

local test ={}

local test =  array_sub(remove, full)

for i = 1, #test do
  print (test[i])
end

function array_sub(t1, t2)
  local t = {}
  for i = 1, #t1 do
    t[t1[i]] = true;
  end
  for i = #t2, 1, -1 do
    if t[t2[i]] then
      table.remove(t2, i);
    end
  end
end

交易O(#t1)空间,从O(#t1 * #t2)到O(#t1#t2)加速.