You are given a 2D integer array points where points[i] = [xi, yi] represents the coordinates of the ith point on the Cartesian plane.
Return the number of unique trapezoids that can be formed by choosing any four distinct points from points.
A trapezoid is a convex quadrilateral with at least one pair of parallel sides. Two lines are parallel if and only if they have the same slope.
Example 1:
Input: points = [[-3,2],[3,0],[2,3],[3,2],[2,-3]]
Output: 2
Explanation:
There are two distinct ways to pick four points that form a trapezoid:
[-3,2], [2,3], [3,2], [2,-3] form one trapezoid.[2,3], [3,2], [3,0], [2,-3] form another trapezoid.Example 2:
Input: points = [[0,0],[1,0],[0,1],[2,1]]
Output: 1
Explanation:
There is only one trapezoid which can be formed.
Constraints:
4 <= points.length <= 500–1000 <= xi, yi <= 1000