首先可以发现的是,因为两条线段不能在除了端点处相交,因此整个多边形最终一定会被连接成最上方由若干条线段在端点处相交连成,每条线段下方又是一个子结构. 因此你会发现,每个合法的状态都能被分成两个合法的子结构,因此可以考虑使用区间 \(dp\) 来解决这个问题. 首先,我们简单地考虑令 \(dp_{i, j}\) 表示只使用 \(i, j\) 这个区间之间的边将 \(i, j\) 这个区间联通的方案. 直接在 \(i, j\) 之间连边. 那么枚举每个 \(k\) 做为中间的断点,那么就有转移: \…

链接 大意: 给定邻接表表示两点是否可以连接, 要求将图连成树, 且边不相交的方案数 n范围比较小, 可以直接区间dp $f[l][r]$表示答案, $g[l][r]$表示区间[l,r]全部连通且l,r间连边的方案 #include <iostream> #include <algorithm> #include <cstdio> #define PER(i,a,n) for(int i=n;i>=a;--i) #define REP(i,a,n) for(int…

Minimum Cut Time Limit: 10000MS   Memory Limit: 65536K Total Submissions: 9302   Accepted: 3902 Case Time Limit: 5000MS Description Given an undirected graph, in which two vertices can be connected by multiple edges, what is the size of the minimum c…

Minimum Cut Time Limit: 10000MS   Memory Limit: 65536K Total Submissions: 9319   Accepted: 3910 Case Time Limit: 5000MS Description Given an undirected graph, in which two vertices can be connected by multiple edges, what is the size of the minimum c…

Large Scale Distributed Semi-Supervised Learning Using Streaming Approximation Google  2016.10.06 官方 Blog 链接:https://research.googleblog.com/2016/10/graph-powered-machine-learning-at-google.html 今天讲的是一个基于 streaming approximation 的大规模分布式半监督学习框架,出自 Goo…

Alyona and the Tree 题目链接: http://acm.hust.edu.cn/vjudge/contest/121333#problem/C Description Alyona decided to go on a diet and went to the forest to get some apples. There she unexpectedly found a magic rooted tree with root in the vertex 1, every v…

描述 http://poj.org/problem?id=2914 求无向图中最小割. Minimum Cut Time Limit: 10000MS   Memory Limit: 65536K Total Submissions: 8679   Accepted: 3659 Case Time Limit: 5000MS Description Given an undirected graph, in which two vertices can be connected by multi…

Description Given an undirected graph, in which two vertices can be connected by multiple edges, what is the size of the minimum cut of the graph? i.e. how many edges must be removed at least to disconnect the graph into two subgraphs? Input Input co…

Shorten Diameter Time limit : 2sec / Stack limit : 256MB / Memory limit : 256MB Score : 600 points Problem Statement Given an undirected tree, let the distance between vertices u and v be the number of edges on the simple path from u to v. The diamet…

Connect the Graph Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others) Total Submission(s): 108    Accepted Submission(s): 36 Special Judge Problem Description Once there was a special graph. This graph had n vertices a…