Lua阶乘尾零：5因子的配对计数

local function trailingZero(n)
    local f = 1
    for i = 2, n do f = f * i end   -- 大数溢出，尾数全失真
    local c, s = 0, tostring(f)
    for j = #s, 1, -1 do
        if string.sub(s, j, j) == "0" then c = c + 1 end
    end
    return c
end

local function trailingZero(n)
    local c = 0
    while n > 0 do
        n = math.floor(n / 5)
        c = c + n               -- 每层捕获一层5因子
    end
    return c
end
sendmsg(actor, 1, "背包数量100的阶乘尾零 "
    .. trailingZero(100) .. " 个")