题目链接 抄的模版,居然1Y了.就是简单的线段相交+并查集. #include <iostream> #include <cstring> #include <cstdio> #include <cstdlib> #include <cmath> using namespace std; #define eps 1e-8 #define zero(x) (((x) > 0?(x):(-x))<eps) struct point { d…

Jack Straws In the game of Jack Straws, a number of plastic or wooden "straws" are dumped on the table and players try to remove them one-by-one without disturbing the other straws. Here, we are only concerned with if various pairs of straws are…

Jack Straws Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 2911   Accepted: 1322 Description In the game of Jack Straws, a number of plastic or wooden "straws" are dumped on the table and players try to remove them one-by-one witho…

[题目链接] http://poj.org/problem?id=1127 [题目大意] 在二维平面中,给出一些木棍的左右端点,当木棍相交或者间接相交时 我们判断其连通,给出一些询问,问某两个木棍是否连通 [题解] 我们首先记录直接相连的木棍,然后对图跑一遍floyd算法,就能预处理出所有答案. [代码] #include <cstdio> #include <algorithm> #include <cmath> #include <cstring> us…

题意: 给出一系列线段,判断某两个线段是否连通. 思路: 根据线段相交情况建立并查集, 在同一并查集中则连通. (第一反应是强连通分量...实际上只要判断共存即可, 具体的方向啊是没有关系的..) 并查集合并的时候是根节点合并. 快速排斥试验不是必需的, 大规模数据可能是个优化吧. 跨立试验注意共线的情况. 共线判断注意与y 轴平行的情况. #include <cstdio> #include <cstring> #include <cmath> using names…

题意:给定一堆线段,然后有询问,问这两个线段是不是相交,并且如果间接相交也可以. 析:可以用并查集和线段相交来做,也可以用Floyd来做,相交就是一个模板题. 代码如下: #pragma comment(linker, "/STACK:1024000000,1024000000") #include <cstdio> #include <string> #include <cstdlib> #include <cmath> #includ…

题意: 有n个木棍,给出木棍的两个端点的x,y坐标,判断其中某两个线段是否连通(可通过其他线段连通) #include <iostream> #include <cstdio> #include <cstring> #include <cstdlib> #include <cmath> #include <vector> #include <queue> #include <map> #include <…

题意:桌子上放着n根木棍,已知木棍两端的坐标.给定几对木棍,判断每对木棍是否相连.当两根木棍之间有公共点或可以通过相连的木棍间接的连在一起,则认为是相连的. 分析: 1.若线段i与j平行,且有部分重合,则相连.否则,求直线i与直线j交点,再判断该交点是否在两线段上,以确定是否相连. 2.flod整理一下所有的关系. 3.判断点是否在线段上:(线段i,点t) (1)外积(l[i] - t) × (r[i] - t) = 0, 可判断点x是否在直线i上(两向量叉乘为0,两向量平行) (2)内积(l[…

http://poj.org/problem?id=1127   Description In the game of Jack Straws, a number of plastic or wooden "straws" are dumped on the table and players try to remove them one-by-one without disturbing the other straws. Here, we are only concerned wi…

In the game of Jack Straws, a number of plastic or wooden "straws" are dumped on the table and players try to remove them one-by-one without disturbing the other straws. Here, we are only concerned with if various pairs of straws are connected b…