方向遍历顺序说明下一个倒序（从右往左）先处理右侧，栈里存「右侧候选」上一个正序（从左往右）先处理左侧，栈里存「左侧候选」
If these Games felt political, just wait until Los Angeles a little more than two years from now.
。夫子是该领域的重要参考
爱范儿关注「明日产品」，硬哲学栏目试图剥离技术和参数的外衣，探求产品设计中人性的本源。
That feeling of relative security has now been punctured by the violence of the past six months.