Lua电梯调度：先上后下的楼层扫描

local function fcfl(requests)
    local floor, steps = 1, 0
    for _, r in ipairs(requests) do
        steps = steps + math.abs(r - floor)
        floor = r
    end
    return steps
end

local function scan(requests, cur)
    local ups, downs = {}, {}
    for _, r in ipairs(requests) do
        if r >= cur then ups[#ups + 1] = r
        else downs[#downs + 1] = r end
    end
    table.sort(ups)
    table.sort(downs, function(a, b) return a > b end)
    local steps, floor = 0, cur
    for _, f in ipairs(ups) do
        steps = steps + f - floor; floor = f
    end
    for _, f in ipairs(downs) do
        steps = steps + floor - f; floor = f
    end
    return steps
end
local p = getplayerbyname("lift01")
sendmsg(p, 1, "SCAN 行程 " .. scan({3, 7, 2, 9}, 1))