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时间限制:1000ms单点时限:1000ms内存限制:256MB描述现在有一棵有N个带权顶点的树，顶点编号为1,2,...,N。我们定义一条路径的次小(最小)权为它经过的所有顶点（包括起点和终点）中权值次小(最小)顶点的权值。现在给定常数c，你需要求出：存在多少个使得u<v的顶点组(u,v)，满足从 阅读全文
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(留坑待填） Extraction from the C++ Programming Language 4th. ed., Bjarne Stroustrup 31.3.3 Size and Capacity The size is the number of elements in the con 阅读全文
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extraction from The C++ Programming Language 4th. ed., Section 7.7 References, Bjarne Stroustrup To reflect the lvalue/rvalue and const/non-const dist 阅读全文
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传送门 题目大意 给定文本串$S$和若干模式串$\{T\}$, 对每个模式串$T$, 询问$T$是否为$S$的子串. Solution 裸的AC自动机, 也可以用后缀数组做. P.S. 这题数据很弱, 朴素的字符串匹配也能过. Pitfalls 模式串有重复的. 这样, 在建TRIE时就不能直接对每 阅读全文
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Data structures A data structure is a way to store and organize data in order to facilitate access and modifications. Loop invariants We use loop inva 阅读全文
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传送门 时间限制:18000ms单点时限:2000ms内存限制:512MB描述小h拥有$n$位朋友。每位朋友拥有一个数值$V_i$代表他与小h的亲密度。亲密度有可能发生变化。岁月流逝，小h的朋友们形成了一种稳定的树状关系。每位朋友恰好对应树上的一个节点。每次小h想请两位朋友一起聚餐，他都必须把连接两 阅读全文
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How do I use software from a PPA? To start installing and using software from a Personal Package Archive, you first need to tell Ubuntu where to find 阅读全文
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Extraction from C++ Primer 5th. Editioin 3.2.1 C++ has several different forms of initialization, we should understand how these forms differ from one 阅读全文
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Extraction from C++ primer 5th Edition 7.1.2 The purpose of the const that follows the parameter list of an ordinary member function is to modify the 阅读全文
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传送门 To the moon Time Limit: 4000/2000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others) Problem Description Background To The Moon is a indep 阅读全文