Notepad#

### 题目描述 一开始打出的内容为空。现在你要打出一个长度为 $n$ 的字符串 $s$（全为英文小写字母组成），为此每次你可以进行如下操作中的一种： - 在已打出内容的最后添加一个字符。 - 复制已打出内容的一个连续的子串并加到内容的末尾。 问你能不能在严格小于 $n$ 次操作下打出字符串 $s$？ ### 输入格式 $t$ 组数据。第一行输入正整数 $t(1\le t\le10^4)$。 每组数据第一行输入正整数 $n$，第二行输入字符串 $s$。 单个测试点内所有 $n$ 之和不超过 $2\times10^5$。 ### 输出格式 输出 $t$ 行，每行输出这组数据的答案。如果可以达到要求，输出 `YES`。否则输出 `NO`。

You want to type the string $ s $ , consisting of $ n $ lowercase Latin letters, using your favorite text editor Notepad#. Notepad# supports two kinds of operations: - append any letter to the end of the string; - copy a continuous substring of an already typed string and paste this substring to the end of the string. Can you type string $ s $ in strictly less than $ n $ operations?

The first line contains a single integer $ t $ ( $ 1 \le t \le 10^4 $ ) — the number of testcases. The first line of each testcase contains a single integer $ n $ ( $ 1 \le n \le 2 \cdot 10^5 $ ) — the length of the string $ s $ . The second line contains a string $ s $ , consisting of $ n $ lowercase Latin letters. The sum of $ n $ doesn't exceed $ 2 \cdot 10^5 $ over all testcases.

For each testcase, print "YES" if you can type string $ s $ in strictly less than $ n $ operations. Otherwise, print "NO".

6
10
codeforces
8
labacaba
5
uohhh
16
isthissuffixtree
1
x
4
momo

NO
YES
NO
YES
NO
YES

In the first testcase, you can start with typing "codef" ( $ 5 $ operations), then copy "o" ( $ 1 $ operation) from an already typed part, then finish with typing "rces" ( $ 4 $ operations). That will be $ 10 $ operations, which is not strictly less than $ n $ . There exist other ways to type "codeforces". However, no matter what you do, you can't do less than $ n $ operations. In the second testcase, you can type "labac" ( $ 5 $ operations), then copy "aba" ( $ 1 $ operation), finishing the string in $ 6 $ operations.