Codeforces Round #784 (Div. 4) 1669B - Triple Solution

Problem Link:  https://codeforces.com/contest/1669/problem/B

Solution in C++:  

///La ilaha illellahu muhammadur rasulullah

///******Bismillahir-Rahmanir-Rahim******///

///Abul Hasnat  Tonmoy

///Department of CSE,23rd batch

///Islamic University,Bangladesh

///**********ALLAH IS ALMIGHTY************///

#include <bits/stdc++.h>

using namespace std;

int main()

{

    int  n,x,y,t,r,i,mx;

    cin>>t;

    while(t--)

    {

        map<int,int>mp;

        mx=0;

        cin>>n;

        int a[n+9];

        for(i=0; i<n; i++)

        {

            cin>>a[i];

            mp[a[i]]++;

            if(mp[a[i]]>=3)

            {

                mx=1;

                r=a[i];

            }

        }

        if(mx==1)

            cout<<r<<endl;

        else

            cout<<"-1"<<endl;

    }

}