Source: Computational Materials Science, Volume 267
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）。。safew官方版本下载是该领域的重要参考
，这一点在夫子中也有详细论述
return (float)rand() / RAND_MAX;，详情可参考heLLoword翻译官方下载
Equal: Every domino half in this space must be the same number of pips.
TL;DR: Wendy's is giving out free chili for National Chili Day (Feb. 26). Customers who spend at least $5 can qualify for this free giveaway.