Lua埃氏筛：批量素数的标记排除

local function isPrime(n)
    for i = 2, n - 1 do
        if n % i == 0 then return false end   -- 每个数独立试除
    end
    return true
end

local function sieve(n)
    local mark, count = {}, 0
    for i = 2, n do
        if not mark[i] then
            count = count + 1
            for j = i * i, n, i do
                mark[j] = true          -- 标记倍数，一次排除一片
            end
        end
    end
    sendmsg(actor, 1, "背包数量500格编号中素数 " .. count .. " 个")
end
sieve(500)