**思路:**直接找俩一样的数字看看他们中间是否存在大于等于1个数的情况

#include<iostream>
#include<algorithm>
#include<map>
using namespace std;
long long T,n,sum;
int arr[6005];
map<int, int>mm;
int main()
{
    cin >> T;
    while (T--){//组数
        bool st = 0;
        sum = 0;
        cin >> n;
        for (int i = 1; i <= n; i++) {
            cin >> arr[i];
            mm[arr[i]]++;
            if(mm[arr[i]]>=1)
                for (int j = 1; j <= n; j++)
                {
                    if (arr[j] == arr[i] && i - j > 1)
                        st = 1;
                }
        }
        if (!st) cout << "NO" << endl;
        else cout << "YES" << endl;
    }

    return 0;
}