words.lua

local bylen = {}
for i=1,99 do bylen[i] = {} end
for word in io.lines("/usr/share/dict/words") do
  if #word % 2 == 0 then
    local bucket = bylen[#word]
    bucket[#bucket+1] = word:lower()
  end
end

for i=2,99,2 do
  local prefixes = {}
  local suffixes = {}
  local joints = {}
  local half = i/2
  for _,word in ipairs(bylen[i]) do
    local prefix = word:sub(1,half)
    local suffix = word:sub(half+1)
    prefixes[prefix] = true
    suffixes[suffix] = true
  end
  for prefix,_ in pairs(prefixes) do
    if suffixes[prefix] then
      joints[prefix] = {{},{}}
    end
  end
  for _,word in ipairs(bylen[i]) do
    local prefix = word:sub(1,half)
    local suffix = word:sub(half+1)
    if joints[prefix] then
      joints[prefix][2][word] = true
    end
    if joints[suffix] then
      joints[suffix][1][word] = true
    end
  end
  for _,stuff in pairs(joints) do
    for first, _ in pairs(stuff[1]) do
      for second, _ in pairs(stuff[2]) do
        print(first, second)
      end
    end
  end
end

removed dependencies