Ninja and Substrings Problem Statement

Ninja has to determine all the distinct substrings of size two that can be formed from a given string 'STR' comprising only lowercase alphabetic characters. These substrings must appear as contiguous sequences in 'STR'.

Example:

Input:

"abcd"

Output:

["ab", "bc", "cd"]

Input:

The first line contains a single integer 'T' representing the number of test cases. The next 'T' lines each contain a string 'STR'.

Output:

For each test case, output all unique contiguous substrings of size two from 'STR'. Each test case result should be presented on a new line.

Constraints:

• 1 <= T <= 5*10³
• 2 <= |STR| <= 10³
• Time limit: 1 sec

Note:

You are not required to print anything; it has been handled for you internally.