思路：找「右侧第一个 ≤ cur」的元素 → 弹出所有 cur 的元素，栈顶即为折扣。最终价格 = cur - 折扣（有则）或 cur（无则）。
TL;DR: The Pokémon TCG: Mega Charizard X Tin and Mega Charizard Y Tins are available to preorder for $44.95 and $44.90 at Amazon — up to $7 off their typical list prices ahead of the Feb. 27 release.。雷电模拟器官方版本下载对此有专业解读
ВсеПолитикаОбществоПроисшествияКонфликтыПреступность。爱思助手下载最新版本对此有专业解读
We, the undersigned organizations representing civil society, nonprofit institutions, and technology companies, write to express our strong opposition to Google’s announced policy requiring all Android app developers to register centrally with Google themselves in order to distribute applications outside of the Google Play Store, set to take effect worldwide in the coming months.
// 易错点2：漏写stack.length判断 → 栈空时访问stack[-1]会报错