Custom Sort String

PROBLEM STATEMENT

You are provided with the two strings named X and Y respectively. Y has its own specific order and has no repeating characters. Your task is to arrange the characters of the first string i.e. X in such a way that the order of characters in X is exactly the same as in Y, which means if ‘d’ occurs after ‘c’ in Y then it should also occur after ‘c’ in X ( obviously if X has ‘d’ and ‘c’ as characters in it ). All you have to do is, convert string X in the specific order with respect to string Y.

Note :

Both the strings have only lowercase English alphabets. 
There may be more than one correct solution, you have to return any one of the possible solutions.

Input format:

The first line of input contains an integer ‘T’ denoting the number of test cases.

Then the T test cases follow.

The first line of each test case contains the string X.
The second line of each test case contains the string Y.

Output format:

For each test case, print the string X after converting string X in the specific order with respect to string Y.

The output of each test case is printed in a separate line.

Note:

You do not need to print anything, it has already been taken care of. Just implement the given function.

Constraints :

1 <= T <= 10
1 <= |X| <= 10000
1 <= |Y| <= 26
where ‘T’ is the number of test cases, |X| is the length of the first string and |Y| is the length of the second string.
Time Limit: 1 sec

Approach 1

The idea is to follow the order in which the characters occur in string Y. We have to run two nested loops on strings Y and X respectively and if Yi is the same as Xj then pick this character and add it to the answer string.
For the remaining characters of X that are not in the string Y, we have to just add those characters in our answer string. To find those remaining characters we can create a vector of visited characters or a hash set.

Try Problem