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Unit1-Book2 预习学案 pass ... on to future generations cultural heritage sites work creatively to protect the temple use context clues the cyprecesses planted on Mount Tai take part in a youth project cultural relics the former palace create Monut Tai App/AppCF1267G Game Relics
https://www.luogu.com.cn/problem/CF1267G 麻了，回头看的时候一下子不会算贡献了 白写了可还行 首先考虑抽卡的期望，假设已经抽了\(i\)个圣遗物出来，要出\(i+1\)个圣遗物的期望是 \(E(i)=\frac{i}{n}(E(i)+\frac{x}{2})+\frac{n-i}{n}\times(x+E(i+1))\) \(E(i)-E(i+1)=(\frac{n}{n-