Alphabetical Strings

题意翻译

### 题目描述 若一个长度为 $n$ 的字符串 $s$ 是用以下方法构造的，我们称 $s$ 合法。 - $s$ 初始为空； - 对 $s$ 进行 $n$ 操作，第 $i$ 次操作可以将字典序中排名第 $i$ 的字符插入到 $s$ 的最前面或最后面。 题目给定 $t$ 个字符串，请你分别判断它们是否合法。 ### 输入格式 第一行包含一个整数 $t$。 接下来的 $t$ 行，每行各有一个长度在 $1$ 到 $26$ 之间字符串 $s$。 ### 输出格式 对于每个字符串输出 `YES` 或 `NO`（你也可以输出 `yEs`，`yes` 之类的东西qwq），中间用一个换行隔开。

题目描述

A string $ s $ of length $ n $ ( $ 1 \le n \le 26 $ ) is called alphabetical if it can be obtained using the following algorithm: - first, write an empty string to $ s $ (i.e. perform the assignment $ s $ := ""); - then perform the next step $ n $ times; - at the $ i $ -th step take $ i $ -th lowercase letter of the Latin alphabet and write it either to the left of the string $ s $ or to the right of the string $ s $ (i.e. perform the assignment $ s $ := $ c+s $ or $ s $ := $ s+c $ , where $ c $ is the $ i $ -th letter of the Latin alphabet). In other words, iterate over the $ n $ first letters of the Latin alphabet starting from 'a' and etc. Each time we prepend a letter to the left of the string $ s $ or append a letter to the right of the string $ s $ . Strings that can be obtained in that way are alphabetical. For example, the following strings are alphabetical: "a", "ba", "ab", "bac" and "ihfcbadeg". The following strings are not alphabetical: "z", "aa", "ca", "acb", "xyz" and "ddcba". From the given string, determine if it is alphabetical.

输入输出格式

输入格式

The first line contains one integer $ t $ ( $ 1 \le t \le 10^4 $ ) — the number of test cases. Then $ t $ test cases follow. Each test case is written on a separate line that contains one string $ s $ . String $ s $ consists of lowercase letters of the Latin alphabet and has a length between $ 1 $ and $ 26 $ , inclusive.

输出格式

Output $ t $ lines, each of them must contain the answer to the corresponding test case. Output YES if the given string $ s $ is alphabetical and NO otherwise. You can output YES and NO in any case (for example, strings yEs, yes, Yes and YES will be recognized as a positive answer).

输入输出样例

输入样例 #1

11
a
ba
ab
bac
ihfcbadeg
z
aa
ca
acb
xyz
ddcba

输出样例 #1

YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO

说明

The example contains test cases from the main part of the condition.