Lua最大公约数：辗转相除的循环写法

-- 错误：从小到大逐个试除，命中最晚的那个
local g = 1
for i = 2, math.min(a, b) do
    if a % i == 0 and b % i == 0 then
        g = i
    end
end

local function gcd(a, b)
    while b > 0 do
        a, b = b, a % b
    end
    return a
end
local label = panel:getChildByName("gcdText")
label:setString(tostring(gcd(48, 18)))