只有下面两种情况满足条件：
1. 只有一个数字
2. 只有两个数字且两个数字不相邻

#pragma GCC optimize(2)
#pragma GCC optimize(3)
#include "bits/stdc++.h"
using namespace std;
#define ios ios::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define fios ofstream("test.txt");cout.rdbuf(out.rdbuf())
#define endl "\n"
#define INF 0x3f3f3f3f
#define MINF 2147483647
#define eps 1e-6
#define PI acos(-1)
#define lowbit(x) (x & (-x))
typedef long long LL;
typedef unsigned long long ULL;
typedef pair<int, int> PII;
#define x first
#define y second
const int N = 100010;

int n;

int main()
{
    int T;
    cin >> T;
    while(T--)
    {
        cin >> n;

        vector<int> a(n);
        for(int i = 0; i < n; i++)
        {
            cin >> a[i];
        }

        if(a.size() == 1) cout << "YES" << endl;
        else if(a.size() == 2 && abs(a[0] - a[1]) != 1) cout << "YES" << endl;
        else cout << "NO" << endl;
    }

    return 0;
}