Surround the Trees Problem Description There are a lot of trees in an area. A peasant wants to buy a rope to surround all these trees. So at first he must know the minimal required length of the rope. However, he does not know how to calculate it. Ca…

1.HDU 1392 Surround the Trees 2.题意:就是求凸包周长 3.总结:第一次做计算几何,没办法,还是看了大牛的博客 #include<iostream> #include<cstring> #include<cmath> #include<queue> #include<algorithm> #include<cstdio> #include<cstdlib> #define F(i,a,b) f…

Surround the Trees Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 10803    Accepted Submission(s): 4187 Problem Description There are a lot of trees in an area. A peasant wants to buy a rope t…

Surround the Trees:http://acm.hdu.edu.cn/showproblem.php?pid=1392 题意: 在给定点中找到凸包,计算这个凸包的周长. 思路: 这道题找出凸包上的点后,s数组中就是按顺序的点,累加一下距离就是周长了. #include <algorithm> #include <iterator> #include <iostream> #include <cstring> #include <cstdli…

题目链接:HDU 1392 Problem Description There are a lot of trees in an area. A peasant wants to buy a rope to surround all these trees. So at first he must know the minimal required length of the rope. However, he does not know how to calculate it. Can you…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=1392 这里介绍一种求凸包的算法:Graham.(相对于其它人的解释可能会有一些出入,但大体都属于这个算法的思想,同样可以解决凸包问题) 相对于包裹法的n*m时间,Graham算法在时间上有很大的提升,只要n*log(n)时间就够了.它的基本思想如下: 1.首先,把所有的点按照y最小优先,其次x小的优先排序 2.维护一个栈,用向量的叉积来判断新插入的点跟栈顶的点哪个在外围,如果栈顶的点在当前插入的点的…

题目地址:http://acm.hdu.edu.cn/showproblem.php?pid=1392 题意:给出一些点的坐标,求最小的凸多边形把所有点包围时此多边形的周长. 解法:凸包ConvexHull 模板题 #include<iostream> #include<cstdio> #include<cstring> #include<cmath> #include<cstdlib> #include<algorithm> #de…

http://acm.hdu.edu.cn/showproblem.php?pid=1392 题目大意: 二维平面给定n个点,用一条最短的绳子将所有的点都围在里面,求绳子的长度. 解题思路: 凸包的模板.凸包有很多的算法.这里用Adrew. 注意这几组测试数据 1 1 1 3 0 0 1 0 2 0 输出数据 0.00 2.00 #include<cmath> #include<cstdio> #include<algorithm> using namespace st…

Problem Description There are a lot of trees in an area. A peasant wants to buy a rope to surround all these trees. So at first he must know the minimal required length of the rope. However, he does not know how to calculate it. Can you help him? The…

Surround the Trees Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 10403    Accepted Submission(s): 4033 Problem Description There are a lot of trees in an area. A peasant wants to buy a rope to…

Surround the Trees Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 10345    Accepted Submission(s): 4009 Problem Description There are a lot of trees in an area. A peasant wants to buy a rope to…

题目链接 题意 : 让你找出最小的凸包周长 . 思路 : 用Graham求出凸包,然后对每条边求长即可. Graham详解 #include <stdio.h> #include <string.h> #include <iostream> #include <math.h> #include <algorithm> using namespace std ; struct point { int x,y ; }p[],p1[]; int n ;…

又是一道模板题 #include <iostream> #include <cstring> #include <cstdlib> #include <cstdio> #include <queue> #include <cmath> #include <algorithm> using namespace std; struct P { int x,y; double angle; } p[50010]; bool cm…

//用的自己的计算几何模板,不过比较慢嘿嘿 //要注意只有一个点和两个点 //Computational Geometry //by kevin_samuel(fenice) Soochow University //temple #include <iostream> #include <cmath> #include <algorithm> #include <cstdio> //#include <stack> using namespac…

There are a lot of trees in an area. A peasant wants to buy a rope to surround all these trees. So at first he must know the minimal required length of the rope. However, he does not know how to calculate it. Can you help him? The diameter and length…

传送门:Surround the Trees 题意:求凸包的周长. 分析:凸包模板题,先按极角排好序后,然后根据叉积正负确定凸包. #include <stdio.h> #include <math.h> #include <algorithm> #include <string.h> #include <math.h> using namespace std; ; ; int sgn(double x) { ; ); ; } struct Po…

题面 懒得粘贴了... 大致题意:坐标系内有若干个点,问把这些点都圈起来的最小凸包周长. 题解 直接求出凸包,统计一遍答案即可 #include<iostream> #include<cstdio> #include<cstdlib> #include<cstring> #include<cmath> #include<queue> #include<algorithm> using namespace std; #def…

<题目链接> 题目大意: 给出一些点,让你求出将这些点全部围住需要的多长的绳子. Andrew算法 #include<iostream> #include<cstdio> #include<cstring> #include<algorithm> #include<cmath> using namespace std; struct node{ int x,y; }; node vex[]; bool cmp1(node a,node…

题意:给一堆二维的点,问你最少用多少距离能把这些点都围起来 思路: 凸包: 我们先找到所有点中最左下角的点p1,这个点绝对在凸包上.接下来对剩余点按照相对p1的角度升序排序,角度一样按距离升序排序.因为凸包有一个特点,从最左下逆时针走,所有线都在当前这条向量的左边,根据这个特点我们进行判断.我们从栈顶拿出两个点s[top-1],s[top],所以如果s[top-1] -> p[i] 在 s[top-1] -> s[top] 右边,那么s[top]就不是凸包上一点,就这样一直判断下去.判断左右可…

Surround the Trees Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Problem Description There are a lot of trees in an area. A peasant wants to buy a rope to surround all these trees. So at first he must know the mi…

Surround the Trees Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 6728    Accepted Submission(s): 2556 Problem Description There are a lot of trees in an area. A peasant wants to buy a rope to…

Surround the Trees Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 6812    Accepted Submission(s): 2594 Problem Description There are a lot of trees in an area. A peasant wants to buy a rope to…

Surround the Trees Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 7043    Accepted Submission(s): 2688 Problem Description There are a lot of trees in an area. A peasant wants to buy a rope to…

Problem Description There are a lot of trees in an area. A peasant wants to buy a rope to surround all these trees. So at first he must know the minimal required length of the rope. However, he does not know how to calculate it. Can you help him? The…

HDU 1000 A + B Problem  I/O HDU 1001 Sum Problem  数学 HDU 1002 A + B Problem II  高精度加法 HDU 1003 Maxsum  贪心 HDU 1004 Let the Balloon Rise  字典树,map HDU 1005 Number Sequence  求数列循环节 HDU 1007 Quoit Design  最近点对 HDU 1008 Elevator  模拟 HDU 1010 Tempter of th…

一直听大佬们说:凸包.凸包.凸包 一直不会..... 然后.... 今天考试,考了一道计算几何的简单题.... 这,,,还是学一下吧.. 然后考试现场学习一下凸包算法. 先理解一下凸包是啥东西. 看看这张图 解释一下凸包是什么 如果你有一堆点(原谅我画的很凌乱) 那么,找到一个点集 依次连接这些点 使他们形成一个凸多边形 并且所有的点都包括在这个多边形的内部或者边上 这个多边形就是一个凸包(我写的肯定一点也不严谨) 不管怎么样,就先这样理解一下吧...... 凸包是啥应该不难理解,那么,给你一堆…

凸包真是一个神奇的算法.. 概念 凸包,我理解为凸多边形 叉积 对于向量AB和向量BC,记向量AB*向量BC = AB * BC * sin ∠ABC,而叉积的绝对值其实就是S△ABC/2 对于平面上的一些点,我们要求凸包上所有的点,可以使用Graham算法 时间复杂度O(nlogn) 思路 先找到最左下的点,把其他的点按叉积排序.然后维护一个堆栈,每次利用叉积和栈顶比较判断当前枚举到的点是否是凸包上的点,是则弹出栈顶元素 具体算法Click here 周长 直接所有相邻两点距离相加 面积 多边…

题目链接:hdu 3842 Machine Works 详细题解: HDU 3842 Machine Works cdq分治 斜率优化 细节比较多,好好体会一下. 在维护斜率的时候要考虑x1与x2是否相等,这里要处理一下. #include<bits/stdc++.h> #define F(i,a,b) for(int i=a;i<=b;i++) using namespace std; typedef long long ll; typedef pair<int,ll>P;…

分析:直接求出凸包.再算边长就可以. 另外仅仅有一个点时为0.00单独处理,两个点直接为距离也单独处理. #include<iostream> #include<cmath> #include<algorithm> using namespace std; struct Point { Point(){} Point(double _x,double _y):x(_x),y(_y){} Point operator-(const Point& a) const…

<题目链接> Problem Description “ 改革春风吹满地,不会AC没关系;实在不行回老家,还有一亩三分地.谢谢!(乐队奏乐)” 话说部分学生心态极好,每天就知道游戏,这次考试如此简单的题目,也是云里雾里,而且,还竟然来这么几句打油诗.好呀,老师的责任就是帮你解决问题,既然想种田,那就分你一块.这块田位于浙江省温州市苍南县灵溪镇林家铺子村,多边形形状的一块地,原本是linle 的,现在就准备送给你了.不过,任何事情都没有那么简单,你必须首先告诉我这块地到底有多少面积,如果回答正确…