CF1506G.Maximize the Remaining String

You are given a string $s$, consisting of lowercase Latin letters. While there is at least one character in the string $s$ that is repeated at least twice, you perform the following operation:

• you choose the index $i$ ($1 \le i \le |s|$) such that the character at position $i$ occurs at least two times in the string $s$, and delete the character at position $i$, that is, replace $s$ with $s_1 s_2 \ldots s_{i-1} s_{i+1} s_{i+2} \ldots s_n$.

For example, if $s=$"codeforces", then you can apply the following sequence of operations:

• $i=6 \Rightarrow s=$"codefrces";
• $i=1 \Rightarrow s=$"odefrces";
• $i=7 \Rightarrow s=$"odefrcs";

Given a given string $s$, find the lexicographically maximum string that can be obtained after applying a certain sequence of operations after which all characters in the string become unique.

A string $a$ of length $n$ is lexicographically less than a string $b$ of length $m$, if:

• there is an index $i$ ($1 \le i \le \min(n, m)$) such that the first $i-1$ characters of the strings $a$ and $b$ are the same, and the $i$-th character of the string $a$ is less than $i$-th character of string $b$;
• or the first $\min(n, m)$ characters in the strings $a$ and $b$ are the same and $n \lt m$.

For example, the string $a=$"aezakmi" is lexicographically less than the string $b=$"aezus".

给你一个由小写拉丁字母组成的字符串 $s$。只要字符串 $s$ 中至少存在一个字符出现次数不少于两次，你就执行如下操作：

• 选择一个下标 $i$（$1 \le i \le |s|$），使得位置 $i$ 上的字符在字符串 $s$ 中至少出现两次，并删除该位置上的字符，即用 $s_1 s_2 \ldots s_{i-1} s_{i+1} s_{i+2} \ldots s_n$ 替换 $s$。

例如，若 $s =$ "codeforces"，则可执行如下操作序列：

• $i = 6 \Rightarrow s =$ "codefrces"；
• $i = 1 \Rightarrow s =$ "odefrces"；
• $i = 7 \Rightarrow s =$ "odefrcs"。

给定字符串 $s$，求在执行若干次上述操作（使得最终字符串中所有字符互不相同）后，所能得到的字典序最大的字符串。

长度为 $n$ 的字符串 $a$ 在字典序上小于长度为 $m$ 的字符串 $b$，当且仅当满足以下任一条件：

• 存在某个下标 $i$（$1 \le i \le \min(n, m)$），使得字符串 $a$ 和 $b$ 的前 $i-1$ 个字符完全相同，且 $a$ 的第 $i$ 个字符严格小于 $b$ 的第 $i$ 个字符；
• 或字符串 $a$ 和 $b$ 的前 $\min(n, m)$ 个字符完全相同，且 $n \lt m$。

例如，字符串 $a =$ "aezakmi" 在字典序上小于字符串 $b =$ "aezus"。

The first line contains one integer $t$ ($1 \le t \le 10^4$). Then $t$ test cases follow.

Each test case is characterized by a string $s$, consisting of lowercase Latin letters ($1 \le |s| \le 2 \cdot 10^5$).

It is guaranteed that the sum of the lengths of the strings in all test cases does not exceed $2 \cdot 10^5$.

第一行包含一个整数 $t$（$1 \le t \le 10^4$）。随后是 $t$ 组测试用例。

每组测试用例由一个字符串 $s$ 描述，该字符串仅由小写拉丁字母组成（$1 \le |s| \le 2 \cdot 10^5$）。

保证所有测试用例中字符串长度的总和不超过 $2 \cdot 10^5$。

For each test case, output the lexicographically maximum string that can be obtained after applying a certain sequence of operations after which all characters in the string become unique.

对于每个测试用例，输出在执行某一操作序列后所能得到的字典序最大的字符串，使得该字符串中所有字符均互不相同。