一个很玄乎的问题,但听到2-SAT之后就豁然开朗了.题目的意思是这样的,给你n个点群,每个点群里面有两个点,你要在每个点群里面选一个点,以这些点做半径为r的圆,然后r会有一个最大值,问的就是怎么选这些点使得r最大. 2-SAT就是对于每个变量有一些制约的关系   a->b 表示选了a就就要选b.然后我们二分这个半径,对于两点间距离<2*r的点(a,b)选了a就不能选b,选了b就不能选a,以此构图.然后跑一次强连通分量.最后判是否有解的时候就是判对于两个属于相同点群的点,它们不能处于同一强连通分…

检测凸多边形碰撞的一种简单的方法是SAT(Separating Axis Theorem),即分离轴定理. 原理:将多边形投影到一条向量上,看这两个多边形的投影是否重叠.如果不重叠,则认为这两个多边形是分离的,否则找下一条向量来继续投影.我们不需要比较很多条向量,因为已经在数学上证明,多边形每条边的垂直向量就是我们需要的向量. 1.AABB 让我们首先以AABB开始(AABB是一种两边分别平行于X-Y轴的矩形) 判断两个AABB是否碰撞,我们只需要投影两次,分别是投影在平行于X轴和Y轴的向量上…

Problem Description Contest time again! How excited it is to see balloons floating around. But to tell you a secret, the judges' favorite time is guessing the most popular problem. When the contest is over, they will count the balloons of each color…

Let the Balloon Rise Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 74110    Accepted Submission(s): 27711 Problem Description Contest time again! How excited it is to see balloons floating aro…

Crashing Balloon Time Limit: 2 Seconds      Memory Limit: 65536 KB On every June 1st, the Children's Day, there will be a game named "crashing balloon" on TV.   The rule is very simple.  On the ground there are 100 labeled balloons, with the num…

Problem Description Contest time again! How excited it is to see balloons floating around. But to tell you a secret, the judges' favorite time is guessing the most popular problem. When the contest is over, they will count the balloons of each color…

Problem Description The contest starts now! How excited it is to see balloons floating around. You, one of the best programmers in HDU, can get a very beautiful balloon if only you have solved the very very very... easy problem.Give you an operator (…

Let the Balloon Rise Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 87647    Accepted Submission(s): 33130 Problem Description Contest time again! How excited it is to see balloons floating ar…

Let the Balloon Rise Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 104108    Accepted Submission(s): 40046 Problem Description Contest time again! How excited it is to see balloons floating ar…

Let the Balloon Rise Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 106421 Accepted Submission(s): 41214 Problem Description Contest time again! How excited it is to see balloons floating around.…