Codeforces Cards

#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<algorithm>
#include<map>

using namespace std;

#define sf scanf
#define pf printf

typedef map<int , bool>mpbi;

int ar[110];

int main()
{
    int n;
    mpbi mp;
    while(~sf("%d", &n))
    {
        int i,j, sum=0;

        mp.clear();

        for(i=1; i<=n; i++)
        {
            sf("%d", &ar[i]);
            sum+=ar[i];
        }

        sum = sum / (n / 2); //cout << sum;

        int k=0;

        for(i=1; i<=n; i++)
        {
            for(j=i+1; j<=n; j++)
            {
                if(ar[i] + ar[j] == sum)
                {
                    //pf("%d %d\n", i, j);
                    //break;
                    if(!mp[i] and !mp[j])
                    {
                       mp[i]=true;
                       mp[j] = true;
                       pf("%d %d\n", i, j);
                    }
                }
            }
        }
    }

    return 0;
}