C1. Balanced Removals (Easier)

http://codeforces.com/contest/1237/problem/C1 

#include <bits/stdc++.h>
//#include <cmath>
//#include <iostream>
//#include <unordered_map>

#define lowbit(x) ((x)&(-x))
#define mem(x,y) memset(x,y,sizeof(x))
#define pb push_back
#define INF 0x3f3f3f3f
#define ll long long
#define FAST_IO ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
using namespace std;

const int mod=1e9+7;
const int N=1e5+9;

struct node
{
    int id;
    int x,y,z;
}p[N];

bool vis[N];

bool cmp(node a,node b)
{
    if(a.x==b.x)
    {
        if(a.y==b.y) return a.z<b.z;
        return a.y<b.y;
    }
    return a.x<b.x;
}

int main()
{
    FAST_IO;

    int n;
    cin>>n;

    for(int i=1;i<=n;i++)
    {
        p[i].id=i;
        cin>>p[i].x>>p[i].y>>p[i].z;
    }


    for(int i=1;i<=n;i++)
    {
        if(vis[i]) continue;
        int x=p[i].x;
        int y=p[i].y;
        int z=p[i].z;
        ll d=1e9;
        int id=0;
        for(int j=1;j<=n;j++)
        {
            if(i==j) continue;
            ll dis=abs(p[j].x-x)+abs(p[j].y-y)+abs(p[j].z-z);
            if(!vis[j]&&dis<d)
            {
                id=j;
                d=dis;
            }
        }

        vis[i]=1;
        vis[id]=1;
        cout<<i<<" "<<id<<endl;

    }



    return 0;
}