Lua希尔排序：分组插入的递减步长

local function insertionSlow(t)
    for i = 2, #t do
        local v, j = t[i], i - 1
        while j >= 1 and t[j] > v do
            t[j + 1] = t[j]         -- 乱序表逐个挪，慢
            j = j - 1
        end
        t[j + 1] = v
    end
end

local function shell(t)
    local n = #t
    local gap = math.floor(n / 2)
    while gap >= 1 do
        for i = gap + 1, n do
            local v, j = t[i], i - gap
            while j >= 1 and t[j] > v do
                t[j + gap] = t[j]   -- 组内插入排序
                j = j - gap
            end
            t[j + gap] = v
        end
        gap = math.floor(gap / 2)   -- 步长逐轮减半
    end
    return t
end
sendmsg(actor, 1, "最小矿石价格 " .. shell({30, 10, 50, 20})[1])