12月20日，龙玥城购物中心，市民在购物。新京报记者 王贵彬 摄
When the star eventually releases its outer layers, it shrivels down to its core in what's known as a white dwarf star. At that point, it'll be about the size of Earth.
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The best subject lines are short and to the point, accurately describing the content of the email, but also catchy and intriguing, so the reader wants to know more. Once Again, this is the perfect place for A/B testing, to see what types of subject lines work best with your audience. Your call to action should be clear and simple. It should be somewhere at the top of your email for those who haven't finished reading the entire email, then repeated at the end for those reading all the way through. It should state exactly what you want subscribers to do, for example "Click here to download the premium theme for free.
思路：单调递减栈，找「上一个比当前价格大的元素索引」。正序遍历，弹出所有 ≤ 当前价格的索引；跨度 = 当前索引 - 栈顶索引（栈空则为 当前索引 + 1）。