题目描述
Satyam is given $n$ distinct points on the 2D coordinate plane. It is guaranteed that $0 \leq y_i \leq 1$ for all given points $(x_i, y_i)$. How many different nondegenerate right triangles$^{\text{∗}}$ can be formed from choosing three different points as its vertices?
Two triangles $a$ and $b$ are different if there is a point $v$ such that $v$ is a vertex of $a$ but not a vertex of $b$.
Input
The first line contains an integer $t$ ($1 \leq t \leq 10^4$) — the number of test cases.
The first line of each test case contains an integer $n$ ($3 \leq n \leq 2 \cdot 10^5$) — the number of points.
The following $n$ lines contain two integers $x_i$ and $y_i$ ($0 \leq x_i \leq n$, $0 \leq y_i \leq 1$) — the $i$'th point that Satyam can choose from. It is guaranteed that all $(x_i, y_i)$ are pairwise distinct.
It is guaranteed that the sum of $n$ over all test cases does not exceed $2 \cdot 10^5$.
Output
Output an integer for each test case, the number of distinct nondegenerate right triangles that can be formed from choosing three points.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分
样例输入
样例输出
提示
The four triangles in question for the first test case: