#P13608. [NWRRC 2022] K-Shaped Figures

[NWRRC 2022] K-Shaped Figures

题目描述

Let's say that three segments on a plane form a Kshaped figure{\it K-shaped\ figure} if:

  • two of them share a common endpoint;
  • this common endpoint lies strictly inside the third segment;
  • these two segments are located on the same side with respect to the third one;
  • all three segments are pairwise not collinear.

You are given a collection of nn segments on the plane. Find the number of triples of segments from this collection that form a K-shaped figure.

输入格式

Each test contains multiple test cases. The first line contains the number of test cases tt (1t33331 \le t \le 3333). The description of the test cases follows.

The first line of each test case contains a single integer nn --- the number of segments (3n10003 \le n \le 1000).

The ii-th of the following nn lines contains four integers xi,1x_{i,1}, yi,1y_{i,1}, xi,2x_{i,2}, yi,2y_{i,2} --- the coordinates of endpoints of the ii-th segment ($-10^6 \le x_{i,1}, y_{i,1}, x_{i,2}, y_{i,2} \le 10^6$). All segments have positive lengths. Some segments may coincide.

It is guaranteed that the sum of nn over all test cases does not exceed 10410^4.

输出格式

For each test case, print a single integer --- the number of triples of segments that form a K-shaped figure.

2
5
0 0 0 10
0 5 3 10
0 5 3 0
0 5 7 4
0 5 6 2
8
0 0 10 10
3 4 4 4
4 4 4 5
3 4 4 4
7 7 7 8
7 7 8 7
5 5 4 6
5 5 3 7
6
2