P6620 [CF1617A] Forbidden Subsequence
入门
题目描述

You are given strings $S$ and $T$, consisting of lowercase English letters. It is guaranteed that $T$ is a permutation of the string abc.

Find string $S'$, the lexicographically smallest permutation of $S$ such that $T$ is not a subsequence of $S'$.

String $a$ is a permutation of string $b$ if the number of occurrences of each distinct character is the same in both strings.

A string $a$ is a subsequence of a string $b$ if $a$ can be obtained from $b$ by deletion of several (possibly, zero or all) elements.

A string $a$ is lexicographically smaller than a string $b$ if and only if one of the following holds:

  • $a$ is a prefix of $b$, but $a \ne b$;
  • in the first position where $a$ and $b$ differ, the string $a$ has a letter that appears earlier in the alphabet than the corresponding letter in $b$.

Input

Each test contains multiple test cases. The first line contains a single integer $t$ ($1 \le t \le 1000$) — the number of test cases. Description of the test cases follows.

The first line of each test case contains a string $S$ ($1 \le |S| \le 100$), consisting of lowercase English letters.

The second line of each test case contains a string $T$ that is a permutation of the string abc. (Hence, $|T| = 3$).

Note that there is no limit on the sum of $|S|$ across all test cases.

Output

For each test case, output a single string $S'$, the lexicographically smallest permutation of $S$ such that $T$ is not a subsequence of $S'$.

输入格式

见题面 Input 部分

输出格式

见题面 Output 部分

样例输入
7 abacaba abc cccba acb dbsic bac abracadabra abc dddddddddddd cba bbc abc ac abc
样例输出
aaaacbb abccc bcdis aaaaacbbdrr dddddddddddd bbc ac
提示

In the first test case, both aaaabbc and aaaabcb are lexicographically smaller than aaaacbb, but they contain abc as a subsequence.

In the second test case, abccc is the smallest permutation of cccba and does not contain acb as a subsequence.

In the third test case, bcdis is the smallest permutation of dbsic and does not contain bac as a subsequence.