Peculiar Movie Preferences

题意翻译

## 题目描述 给定一个含有$n$个字符串的序列，序列中的每个字符串长度均不超过$3$，判断能否从中选出一个非零子段（可以不连续），使得子段中的字符串按照在序列中的顺序首尾相连构成一个回文串。如果能，输出"YES"，否则输出"NO"。 ## 输入格式 第一行一个整数$t$（$1 \leq t \leq 100$），表示测试样例的数量 每一组测试样例的第一行一个整数$n$（所有的$n$之和小于等于$10^5$），表示序列中字符串的总数 接下来的$n$行，每行一个非空且长度小于等于3的字符串，只包含小写字母 ## 输出格式 对于每一组测试样例，如果可以构成回文串，则输出"YES"，否则输出"NO"

题目描述

Mihai plans to watch a movie. He only likes palindromic movies, so he wants to skip some (possibly zero) scenes to make the remaining parts of the movie palindromic. You are given a list $ s $ of $ n $ non-empty strings of length at most $ 3 $ , representing the scenes of Mihai's movie. A subsequence of $ s $ is called awesome if it is non-empty and the concatenation of the strings in the subsequence, in order, is a palindrome. Can you help Mihai check if there is at least one awesome subsequence of $ s $ ? A palindrome is a string that reads the same backward as forward, for example strings "z", "aaa", "aba", "abccba" are palindromes, but strings "codeforces", "reality", "ab" are not. A sequence $ a $ is a non-empty subsequence of a non-empty sequence $ b $ if $ a $ can be obtained from $ b $ by deletion of several (possibly zero, but not all) elements.

输入输出格式

输入格式

The first line of the input contains a single integer $ t $ ( $ 1 \le t \le 100 $ ) — the number of test cases. The description of test cases follows. The first line of each test case contains a single integer $ n $ ( $ 1 \le n \le 10^5 $ ) — the number of scenes in the movie. Then follows $ n $ lines, the $ i $ -th of which containing a single non-empty string $ s_i $ of length at most $ 3 $ , consisting of lowercase Latin letters. It is guaranteed that the sum of $ n $ over all test cases does not exceed $ 10^5 $ .

输出格式

For each test case, print "YES" if there is an awesome subsequence of $ s $ , or "NO" otherwise (case insensitive).

输入输出样例

输入样例 #1

6
5
zx
ab
cc
zx
ba
2
ab
bad
4
co
def
orc
es
3
a
b
c
3
ab
cd
cba
2
ab
ab

输出样例 #1

YES
NO
NO
YES
YES
NO

说明

In the first test case, an awesome subsequence of $ s $ is $ [ab, cc, ba] $