[Solution] Antipodal Points solution codechef

Antipodal Points solution codechef – You are given a set of NN distinct points P1,P2,P3,…,PNP1,P2,P3,…,PN on a 22-D plane.

[Solution] Antipodal Points solution codechef

A triplet (i,j,k)(i,j,k) is called a holy triplet if

• 1≤i<j<k≤N1≤i<j<k≤N
• PiPi, PjPj and PkPk are non-collinear and
• Any two of the points PiPi, PjPj and PkPk are antipodal points of the circle that passes through all three of them.

Two points on a circle are said to be antipodal points of the circle if they are diametrically opposite to each other.

Find the total number of holy triplets.

Input Format

• The first line contains a single integer TT – the number of test cases. Then the test cases follow.
• The first line of each test case contains an integer NN – the number of points.
• Each of the next NN lines contains two space separated integers xixi and yiyi, denoting the co-ordinates of ii-th point PiPi.

Output Format

For each test case output a single line denoting the number of holy triplets.

[Solution] Antipodal Points solution codechef

• 1≤T≤101≤T≤10
• 3≤N≤20003≤N≤2000
• Sum of NN over all test cases does not exceed 20002000
• −109≤xi,yi≤109−109≤xi,yi≤109
• All points P1,P2,…,PNP1,P2,…,PN in each test case are distinct.

Sample Input 1 

1
4
0 1
0 -1
1 0
-1 0

Sample Output 1 

4

Antipodal Points solution Explanation

Test case 1: The holy triplets in this case are

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