2018 HDU多校联赛第一场Triangle Partition

题目衔接：http://acm.hdu.edu.cn/showproblem.php?pid=6300

Triangle Partition

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 132768/132768 K (Java/Others)
Total Submission(s): 636    Accepted Submission(s): 326
Special Judge
 

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

 

Source

2018 Multi-University Training Contest 1

 题目大意：让你建造n个三角形，给出3n个点，点都是不在同一直线上的，问每个三角形，使用的点的编号是多少

思路：由于不在同一直线上，所以排个序，输出就好了

代码：

#include<map>
#include<stack>
#include<queue>
#include<cmath>
#include<string>
#include<cstdio>
#include<vector>
#include<cstdlib>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
const int N=1e5;
typedef long long ll;
struct qq
{
    int x,y,id;
}a[N];
int cmp(qq A,qq B)
{
    return A.x<B.x;
}
int main()
{
   int test;
   scanf("%d",&test);
   while(test--)
   {
       int n,i,j,k;
       scanf("%d",&n);
       for(i=1;i<=3*n;i++)
       {
           scanf("%d%d",&a[i].x,&a[i].y);
           a[i].id=i;
       }
       sort(a+1,a+3*n+1,cmp);
       for(i=1;i<=3*n;i+=3)
       {
           printf("%d %d %d\n",a[i].id,a[i+1].id,a[i+2].id);
       }
   }
    return 0;
}