（三）未经批准设置无线电广播电台、通信基站等无线电台（站）的，或者非法使用、占用无线电频率，从事违法活动的。
People across region are bracing for possibility of conflict as embassies evacuate staff and flights are cancelled
。服务器推荐是该领域的重要参考
The Seven Proven Tactics That Actually Work，更多细节参见safew官方版本下载
代码要点：倒序遍历，先算右侧再推左侧；栈内维护「右侧候选更大值」，单调递增（栈顶最小）。