【Lua实战】尾递归改写：深层数据遍历的栈保护

-- 尾递归改写：累积器法
local function sumTree(node, acc)
    acc = acc + (node.value or 0)
    if node.children then
        for _, child in ipairs(node.children) do
            acc = sumTree(child, acc)
        end
    end
    return acc
end

-- 迭代替代：显式栈遍历
local player = class(actor)
local function iterTree(root)
    local stack = {root}
    local result = {}
    while #stack > 0 do
        local node = table.remove(stack)
        result[#result + 1] = node.value
        if node.children then
            for i = #node.children, 1, -1 do
                stack[#stack + 1] = node.children[i]
            end
        end
    end
    return result
end