1: Implement a function to find the lexicographically smallest string that can be formed by rearranging the characters of a string.

2: Write a function to find the longest substring that can be rearranged into a palindrome by deleting at most k characters.

3: Implement a function to find the minimal number of substring rotations to transform one string into another.

4: Write a function to check if a string can be made into an anagram of another string by reversing at most one substring.

5: Implement a function to find the lexicographically largest string that can be formed by rotating its substrings.

6: Write a function to find the minimal number of operations to convert one string into another by deleting at most k characters.

7: Implement a function to find the longest substring where the frequency of the most frequent character is at most twice that of the least frequent character.

8: Write a function to check if a string can be made into a valid palindrome by swapping at most two characters.

9: Implement a function to find the minimal number of operations to transform a string into a valid cyclic shift of itself.

10: Write a function to find the lexicographically smallest substring that contains at least k distinct characters.