#P9875. [EC Final 2021] Two Walls

    ID: 9253 Type: RemoteJudge 4000ms 1024MiB Tried: 0 Accepted: 0 Difficulty: 6 Uploaded By: Tags>计算几何2021O2优化ICPC

[EC Final 2021] Two Walls

题目描述

Prof. Pang has bought a humanoid cleaning robot to clean his yard. The robot is not very sophisticated. It can either move forward or change its direction at a time, all controlled by Prof. Pang's controller.

Prof. Pang's yard is a 2D plane. The robot needs to move from its current location AA to the destination BB to fulfill some cleaning needs of Prof. Pang. However, there are two straight walls CDCD and EFEF in Prof. Pang's yard. Since the robot is clumsy, it will fall over if it touches any of the walls (even at endpoints).

Now that Prof. Pang is lazy, he wants to minimize the number of times the robot changes its direction. Can you help him?

输入格式

The first line contains a single integer TT (1T1051 \le T \le 10^5) denoting the number of test cases.

For each test case, the first line contains two integers xA,yAx_A, y_A, the coordinates of point AA. The second line contains two integers xB,yBx_B, y_B, the coordinates of point BB. The third line contains four integers xC,yC,xD,yDx_C, y_C, x_D, y_D, the coordinates of point CC and DD which are the endpoints of the first wall. The fourth line contains four integers xE,yE,xF,yFx_E, y_E, x_F, y_F, the coordinates of point EE and FF which are the endpoints of the second wall.

It is guaranteed that neither the current location AA nor the destination BB of the robot are on any of the walls. A wall may degenerate to a point. It can be proved that the robot can always move from AA to BB without touching any of the walls. All values lie within [109,109][-10^9, 10^9].

输出格式

For each test case, print one number dd in one line, denoting the minimum number of turns.

题目大意

平面直角坐标系上有两点 AABB,以及两面墙 CD,EFCD,EF,墙可以视作线段。

请问从 AABB 在不碰到墙(端点也不可碰到)的情况下最少要转几次弯(转弯的度数可以任意决定)?

3
0 0
1 1
2 2 3 3
4 4 5 5
0 0
1 1
2 2 3 3
2 2 3 3
0 0
10 10
10 0 0 10
1 1 2 2
0
0
1

提示

The following are illustrations for the first sample and the third sample.