Lua跳表：有序集合的跳跃查找

-- 错误：无序链表线性找，一个一个挪
for i, it in ipairs(chain) do
    if it.v == v then
        return i
    end
end

local level2 = {{v = 10, d = 1}, {v = 40, d = 2}}
local level1 = {{v = 10}, {v = 20}, {v = 30},
    {v = 40}, {v = 50}}
local function find(v)
    local lo, hi = 1, #level2
    while lo <= hi do
        local mid = math.floor((lo + hi) / 2)
        if level2[mid].v <= v then lo = mid + 1
        else hi = mid - 1 end
    end
    local start = (level2[lo - 1] or {d = 0}).d
    for i = start, #level1 do
        if level1[i].v == v then return i end
    end
    return nil
end
local label = panel:getChildByName("skipText")
label:setString(tostring(find(30)))