Lua差集运算：已有集合的排除筛选

local function rest(all, owned)
    local out = {}
    for _, v in ipairs(all) do
        local found = false
        for _, o in ipairs(owned) do   -- 双循环平方级
            if v == o then found = true break end
        end
        if not found then out[#out + 1] = v end
    end
    return out
end

local function rest(all, owned)
    local has, out = {}, {}
    for _, o in ipairs(owned) do has[o] = true end
    for _, v in ipairs(all) do
        if not has[v] then
            out[#out + 1] = v          -- 不在已有集合即剩余
        end
    end
    return out
end
sendmsg(actor, 1, "剩余可解锁 "
    .. #rest(ALL, OWNED) .. " 项")