A1128 N Queens Puzzle

#include<iostream>
#include<vector>
#include<map>
#include<string>
#include<cstring>
#include<cstdio>
#include<algorithm>
#include<set>
#include<queue>
using namespace std;
int main()
{
	int n, m;
	cin >> n;
	for (int i = 0; i < n; i++)
	{
		cin >> m;
		vector<int>v(m+1);
		bool flag = true;
		for (int j = 1; j <= m; j++)
		{
			cin >> v[j];
			for (int t = 1; t < j; t++)
			{
				if (v[j] == v[t] || abs(v[j] - v[t]) == abs(j - t)) {
					flag = false;
					break;
				}
			}
		}
		if (flag)
			cout << "YES" << endl;
		else
			cout << "NO" << endl;
	}
}