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…

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)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 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…

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…

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): 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 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…