随笔分类 - CodeForces
摘要：Recently, Pari and Arya did some research about NP-Hard problems and they found the minimum vertex cover problem very interesting. Suppose the graph G
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摘要：Long time ago, there was a great kingdom and it was being ruled by The Great Arya and Pari The Great. These two had some problems about the numbers th
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摘要：Oleg the client and Igor the analyst are good friends. However, sometimes they argue over little things. Recently, they started a new company, but the
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摘要：For a connected undirected weighted graph G, MST (minimum spanning tree) is a subgraph of G that contains all of G's vertices, is a tree, and sum of i
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摘要：A point belongs to a triangle if it lies inside the triangle or on one of its sides. Two triangles are disjoint if there is no point on the plane that
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摘要：Dima the hamster enjoys nibbling different things: cages, sticks, bad problemsetters and even trees! Recently he found a binary search tree and instin
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摘要：One day Natalia was walking in the woods when she met a little mushroom gnome. The gnome told her the following story: Everybody knows that the mushro
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摘要：I guess there's not much point in reminding you that Nvodsk winters aren't exactly hot. That increased the popularity of the public transport dramatic
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摘要：Sherlock Holmes found a mysterious correspondence of two VIPs and made up his mind to read it. But there is a problem! The correspondence turned out t
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摘要：You have been offered a job in a company developing a large social network. Your first task is connected with searching profiles that most probably be
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摘要：题意：给定N点，M边，求添加最少的边使之变为连通图的方案数。 思路：注意题目给出的M边可能带环，即最后生成的不一定是一棵树。但是影响不大。根据矩阵树定理，我们知道生成树的数量=N^(N-2)，即点数^(连通数-2)。 此题把已经连通的看成一个整体，就可以得到数量为N^(cnt-2)，然后考虑连通块内
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摘要：Nowadays all circuses in Berland have a round arena with diameter 13 meters, but in the past things were different. In Ancient Berland arenas in circu
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摘要：De Prezer loves rectangles.He has a n × m rectangle which there is a number in each of its cells. We show the number in the j - th column of the i - t
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摘要：题意：给定字符串char[]，以及Q个操作，操作有三种： 1：pos，chr：把pos位置的字符改为chr 2：pos：问以pos为中心的回文串长度为多长。 3：pos：问以pos，pos+1为中心的回文串长度为多长。 思路：用hash表示一段字符串或者连续子串。我们用BIT记录hash前缀和，那么
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摘要：题意：给定N点M边的有向图，每条边有距离和颜色，一条有效路径上不能有相邻的边颜色相同。现在给定起点S，多次讯问S到点X的最短有效距离。 TLE思路：用二维状态dis(u,c)表示起点到u，最后一条边的颜色是c的最短距离，用map解决了二维空间不足的问题。但是T第151个点。所以需要优化，标解的优化是
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摘要：题意：给定N的棒棒，K种颜色，每个棒棒的两端可以涂色。现在已知所有的线段要么有一端涂色，要么两端都没有涂色，现在要求把所有的没涂色的部分涂色，使得我们可以把涂色后的棒棒分为N/K组，每组的涂色情况相同。 思路：把没有颜色的棒子，看成一端涂色为0，那么现在每个线段都有一端涂色。我们按照数量来排序，然后
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摘要：题意：一个顶点数为N的生成树，对于每个点i，我们按照与i的距离给出顺序，即dis i 1<=dis i 2<=dis i 3<=...，现在让你输出N-1条边，即还原这棵树。 思路：首先应该得到距离为1的点对，那些肯定是树边，然后这样得到的树边可能<N-1，后面不容易判定哪些是树边。搜索什么的都不好
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摘要：Nikita likes tasks on order statistics, for example, he can easily find the kk-th number in increasing order on a segment of an array. But now Nikita
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摘要：After the war, the supersonic rocket became the most common public transportation. Each supersonic rocket consists of two "engines". Each engine is a
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摘要：题意：给定平面上N个点，问是否存在三角形，其面积为S。 思路：选择Y轴，枚举这个Y轴，面积大小只与|y-Y|有关，然后二分，具体的可以先去做BZOJ3707。 具体的： 1，先对点排序，X坐标为第一关键字，Y坐标为第二关键字，从小到大排序。 2，得到C(N,2)条直线，按照它们的斜率为关键字（叉积排
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