Count Number of Trapezoids II
You are given a 2D integer array points where points[i] = [xi, yi] represents the coordinates of the i^th 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
2There are two distinct ways to pick four points that form a trapezoid.
Example 2
Input
points = [[0,0],[1,0],[0,1],[2,1]]Output
1There is only one trapezoid which can be formed.
Constraints
- 4 <= points.length <= 500
- -1000 <= xi, yi <= 1000
- All points are pairwise distinct.