题目:给出一些线段,判断有几个交点. 问题:如何判断两条线段是否相交? 向量叉乘(行列式计算):向量a(x1,y1),向量b(x2,y2): 首先我们要明白一个定理:向量a×向量b(×为向量叉乘),若结果小于0,表示向量b在向量a的顺时针方向:若结果大于0,表示向量b在向量a的逆时针方向:若等于0,表示向量a与向量b平行.(顺逆时针是指两向量平移至起点相连,从某个方向旋转到另一个向量小于180度).如下图: 在上图中,OA×OB = 2 > 0, OB在OA的逆时针方向:OA×OC = -2 <…

You can Solve a Geometry Problem too Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 9596    Accepted Submission(s): 4725 Problem Description Many geometry(几何)problems were designed in the ACM/I…

称号: You can Solve a Geometry Problem too Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 145 Accepted Submission(s): 100   Problem Description Many geometry(几何)problems were designed in the ACM/IC…

You can Solve a Geometry Problem too Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 199    Accepted Submission(s): 132   Problem Description Many geometry(几何)problems were designed in the ACM/…

http://acm.hdu.edu.cn/showproblem.php?pid=1086 You can Solve a Geometry Problem too Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 8861    Accepted Submission(s): 4317 Problem Description Many…

You can Solve a Geometry Problem too Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 12959    Accepted Submission(s): 6373 Problem Description Many geometry(几何)problems were designed in the ACM/…

You can Solve a Geometry Problem too Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 6837 Accepted Submission(s): 3303 Problem Description Many geometry(几何)problems were designed in the ACM/ICPC. A…

You can Solve a Geometry Problem too Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 6425    Accepted Submission(s): 3099 Problem Description Many geometry(几何)problems were designed in the ACM/I…

You can Solve a Geometry Problem too Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 10204    Accepted Submission(s): 5042 Problem Description Many geometry(几何)problems were designed in the ACM/…

pid=1086">You can Solve a Geometry Problem too Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others) Total Submission(s): 6997    Accepted Submission(s): 3385 Problem Description Many geometry(几何)problems were designe…