Lua最长公共前缀：纵向扫描的逐列比较

local function commonPrefix(list)
    if #list == 0 then return "" end
    local first = list[1]
    for pos = 1, #first do
        local ch = first:sub(pos, pos)
        for i = 2, #list do
            if list[i]:sub(pos, pos) ~= ch then
                return first:sub(1, pos - 1)
            end
        end
    end
    return first
end

local function prefixPair(a, b)
    local n = math.min(#a, #b)
    for pos = 1, n do
        if a:sub(pos, pos) ~= b:sub(pos, pos) then
            return a:sub(1, pos - 1)
        end
    end
    return a:sub(1, n)
end
local function prefixFold(list)
    local pre = list[1] or ""
    for i = 2, #list do
        pre = prefixPair(pre, list[i])
        if pre == "" then break end
    end
    return pre
end
local p = getplayerbyname("pfx01")
sendmsg(p, 1, "[" .. prefixFold({"flower", "flow", "flight"}) .. "]")