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Vertex Covers 题目描述 In graph theory, a vertex cover of a graph G is a set of vertices S such that each edge of the graph is incident to at least one ve 阅读全文
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对于一个无向图 G ,它的生成树个数等于其基尔霍夫Kirchhoff矩阵任何一个N-1阶主子式的行列式的绝对值。 所谓的N-1阶主子式就是对于一个任意的一个 r ,将矩阵的第 r 行和第 r 列同时删去得到的新矩阵。 基尔霍夫Kirchhoff矩阵的一种求法:基尔霍夫Kirchhoff矩阵 K =度 阅读全文
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Acesrc and Travel 题目描述 Acesrc is a famous tourist at Nanjing University second to none. During this summer holiday, he, along with Zhang and Liu, is g 阅读全文
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Nonsense Time 时间限制: 10 Sec 内存限制: 128 MB 题目描述 You a given a permutation p1,p2,…,pn of size n. Initially, all elements in p are frozen. There will be n 阅读全文
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String and Times 题目描述 Now you have a string consists of uppercase letters, two integers A and B. We call a substring wonderful substring when the time 阅读全文
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independent set 1 时间限制:C/C++ 1秒,其他语言2秒空间限制:C/C++ 102400K,其他语言204800K64bit IO Format: %lld 题目描述 Note: For C++ languages, the memory limit is 100 MB. Fo 阅读全文
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Blow up the city 题目描述 Country A and B are at war. Country A needs to organize transport teams to deliver supplies toward some command center cities.In 阅读全文