Districts Connection

题意翻译

给出 $n$ 个点的特征值 $a_i$，要求构造一棵树使特征值相同的点之间不直接连边

题目描述

There are $ n $ districts in the town, the $ i $ -th district belongs to the $ a_i $ -th bandit gang. Initially, no districts are connected to each other. You are the mayor of the city and want to build $ n-1 $ two-way roads to connect all districts (two districts can be connected directly or through other connected districts). If two districts belonging to the same gang are connected directly with a road, this gang will revolt. You don't want this so your task is to build $ n-1 $ two-way roads in such a way that all districts are reachable from each other (possibly, using intermediate districts) and each pair of directly connected districts belong to different gangs, or determine that it is impossible to build $ n-1 $ roads to satisfy all the conditions. You have to answer $ t $ independent test cases.

输入输出格式

输入格式

The first line of the input contains one integer $ t $ ( $ 1 \le t \le 500 $ ) — the number of test cases. Then $ t $ test cases follow. The first line of the test case contains one integer $ n $ ( $ 2 \le n \le 5000 $ ) — the number of districts. The second line of the test case contains $ n $ integers $ a_1, a_2, \ldots, a_n $ ( $ 1 \le a_i \le 10^9 $ ), where $ a_i $ is the gang the $ i $ -th district belongs to. It is guaranteed that the sum of $ n $ does not exceed $ 5000 $ ( $ \sum n \le 5000 $ ).

输出格式

For each test case, print: - NO on the only line if it is impossible to connect all districts satisfying the conditions from the problem statement. - YES on the first line and $ n-1 $ roads on the next $ n-1 $ lines. Each road should be presented as a pair of integers $ x_i $ and $ y_i $ ( $ 1 \le x_i, y_i \le n; x_i \ne y_i $ ), where $ x_i $ and $ y_i $ are two districts the $ i $ -th road connects. For each road $ i $ , the condition $ a[x_i] \ne a[y_i] $ should be satisfied. Also, all districts should be reachable from each other (possibly, using intermediate districts).

输入输出样例

输入样例 #1

4
5
1 2 2 1 3
3
1 1 1
4
1 1000 101 1000
4
1 2 3 4

输出样例 #1

YES
1 3
3 5
5 4
1 2
NO
YES
1 2
2 3
3 4
YES
1 2
1 3
1 4