HDU 6300

Problem Description

Chiaki has 3n points p1,p2,…,p3n. It is guaranteed that no three points are collinear.
Chiaki would like to construct n disjoint triangles where each vertex comes from the 3n points.

 

 

Input

There are multiple test cases. The first line of input contains an integer T, indicating the number of test cases. For each test case:
The first line contains an integer n (1≤n≤1000) -- the number of triangle to construct.
Each of the next 3n lines contains two integers xi and yi (−109≤xi,yi≤109).
It is guaranteed that the sum of all n does not exceed 10000.

 

 

Output

For each test case, output n lines contain three integers ai,bi,ci (1≤ai,bi,ci≤3n) each denoting the indices of points the i-th triangle use. If there are multiple solutions, you can output any of them.

 

 

Sample Input

1 1 1 2 2 3 3 5

 

 

Sample Output

1 2 3

 

这个题目，因为output 是输出每个点的索引，所以定义一个结构体，放X Y num  num为索引，然后根据X（或者Y） 用sort， cmp排序，再每隔三个点输出一次num就可以了。难点是在对题意的理解上。