编程介的小学生 2017-12-09 13:05 采纳率: 0.4%
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Convex

Problem Description
Your task is very simple. You will get the coordinates of n points in a plane. It is guaranteed that there are no three points on a straight line. You can choose any four points from these points to construct a quadrangle. Now, please tell me how many convex quadrangles you can construct.

Input
The first line of input contain an integer z (z ≤ 20), indicating the number of test cases.
For each test case, the first line contain an integer n (4 ≤ n ≤ 700), indicating the number of points. Each of the next n lines contains two integers x and y (-1000000 ≤ x, y ≤ 1000000), indicating the coordinate of corresponding point.

Output
For each test case, just output a single integer, the number of convex quadrangles you can construct.

Sample Input
2
4
0 0
0 1
1 0
1 1
4
0 0
1 0
0 1
-1 -1

Sample Output
1
0

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  • threenewbee 2018-04-05 15:51
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