Surround the Trees 此题讨论区里大喊有坑,原谅我没有仔细读题还跳过了坑点. 题意:平面上有n棵树,选一些树用绳子围成一个包围圈,使得所有的树都在这个圈内. 思路:简单凸包入门题,凸包裸模板.在做这个题前建议先去学学:叉积,极角排序,三角形有向面积. 贴上代码以后再复习. struct node { double x,y; } a[N],p[N]; int n,tot;//总点数和凸包上的点数: double dis(node a,node b)//两点间距离 { return…

第一次做凸包,这道题要特殊考虑下,n=2时的情况,要除以二才行. 我是从最左边的点出发,每次取斜率最大的点,一直到最右边的点. 然后从最左边的点出发,每次取斜率最低的点,一直到最右边的点. #include<stdio.h> #include<math.h> #include<algorithm> #include<string.h> using namespace std; const double eps=1e-9; struct node { doub…

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): 7043    Accepted Submission(s): 2688 Problem Description There are a lot of trees in an area. A peasant wants to buy a rope to…

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…

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): 7203    Accepted Submission(s): 2752 Problem Description There are a lot of trees in an area. A peasant wants to buy a rope to…

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…

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…

思路: 凸包模板题. 注意n=1和n=2的情况. 当n=1时,不需要绳子. 当n=2时,绳子长度为两棵树之间距离. 当n≥e时,Graham求凸包即可.最后将凸包上的所有相邻点距离求和. #include<cmath> #include<cstdio> #include<cctype> #include<algorithm> inline int getint() { char ch; while(!isdigit(ch=getchar())); '; )+…

Surround the Trees Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 7164    Accepted Submission(s): 2738 Problem Description There are a lot of trees in an area. A peasant wants to buy a rope to…

[科普]什么是BestCoder?如何参加? Surround the Trees Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 8113    Accepted Submission(s): 3095 Problem Description There are a lot of trees in an area. A peasant…

Surround the Trees Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 9102    Accepted Submission(s): 3481 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): 291    Accepted Submission(s): 140   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): 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 Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 11811    Accepted Submission(s): 4577 Problem Description There are a lot of trees in an area. A peasant wants to buy a rope to…

称号: Maple trees Time Limit: 1000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 177 Accepted Submission(s): 63   Problem Description There are a lot of trees in HDU. Kiki want to surround all the trees with the m…

链接:http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemId=453 Time Limit: 2 Seconds      Memory Limit: 65536 KB 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 r…

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…

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…

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…

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 ;…

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…

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…

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…

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…

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…