暴力

#include<iostream>

using namespace std;

const int N = 1010;
int k, n;
int q[N];

bool isN(int n)
{
    for(int i = 0; i < n; i++){
        for(int j = 0; j < n && j != i; j++){
            if(q[i] == q[j] || abs(q[i] - q[j]) == abs(i - j)) return false;
        }
    }
}

int main()
{
    cin >> k;
    while(k --){
        cin >> n;
        for(int i = 0; i < n; i++) cin >> q[i];
        if(isN(n)) cout << "YES" << endl;
        else cout << "NO" << endl;
    }

    return 0;
}