Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 27110   Accepted: 9045 Description Once upon a time there was a greedy King who ordered his chief Architect to build a wall around the King's castle. The King was so greedy, that he would n…

一.凸包定义 通俗的说就是:一组平面上的点,求一个包含所有点的最小凸多边形,这个最小凸多边形就是凸包. 二.Graham算法思想 概要:Graham算法的主要思想就是,最终形成的凸包,即包围所有点的凸多边形,假定多边形是按逆时针方向生成的,那么多边形内部包围的所有点与多边形每个有向边的关系都是:点在有向边的左边.依照此思想,只要找到一个出发点,然后依此出发点按逆时针方向构建多边形,并保证每加入一条有向边时,都要满足其余点都在该边的左边. ***点与线的关系定义:平面上的三点P1(x1,y1),P…

板题hdu1348Wall 平面凸包问题是计算几何中的一个经典问题 具体就是给出平面上的多个点,求一个最小的凸多边形,使得其包含所有的点 具体形象就类似平面上有若干柱子,一个人用绳子从外围将其紧紧缠绕一圈 Graham算法 直接讲算法 我们将所有点排序,分别求出上凸壳和下凸壳,合起来就是凸包 以上凸壳为例子,我们先将最左边的点加入凸包[可以想象,最左侧的点一定在凸包上] 之后向后查找: 1.若当前凸包内只有一点,那么加入新的点 2.如果当前凸包内不止一个点,检验新加入的点与凸包最后一个点所在直线…

Description Once upon a time there was a greedy King who ordered his chief Architect to build a wall around the King's castle. The King was so greedy, that he would not listen to his Architect's proposals to build a beautiful brick wall with a perfec…

题意: 给你一个由n个点构成的多边形城堡(看成二维),按顺序给你n个点,相邻两个点相连. 让你围着这个多边形城堡建一个围墙,城堡任意一点到围墙的距离要求大于等于L,让你求这个围墙的最小周长(看成二维平面)(结果四舍五入 分析: 凸包问题和这个问题的差别就在于:凸包问题没有"城堡任意一点到围墙的距离要求大于等于L"这个要求 凸包:找到一个凸多边形把这n个点形成的多边形围起来,找到的那个周长最小的凸多边形就是我们所求的凸包 那么这个问题怎么在凸包的基础上解决呢? 我们考虑L,对于求出的凸多…

Wall Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 28157   Accepted: 9401 Description Once upon a time there was a greedy King who ordered his chief Architect to build a wall around the King's castle. The King was so greedy, that he wo…

题目链接 /* Name:nyoj-253-LK的旅行 Copyright: Author: Date: 2018/4/27 15:01:36 Description: zyj的模板 */ #include <iostream> #include <cstdio> #include <algorithm> #include <cstring> using namespace std; ; struct Point { int x, y; Point(, )…

题目链接 /* Name:nyoj-78-圈水池 Copyright: Author: Date: 2018/4/27 9:52:48 Description: Graham求凸包 zyj大佬的模板,改个输出就能用 */ #include <cstring> #include <iostream> #include <cstdio> #include <algorithm> using namespace std; struct point{ double…

Wall Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 3779    Accepted Submission(s): 1066 Problem Description Once upon a time there was a greedy King who ordered his chief Architect to build a…

Time Limit: 3000MS   Memory Limit: 65536K Total Submissions: 25256   Accepted: 7756 Description Bessie, Farmer John's prize cow, has just won first place in a bovine beauty contest, earning the title 'Miss Cow World'. As a result, Bessie will make a…