Smallest Proportion Character Substrings

Given a list of strings, select the strings where the most common character has the smallest proportion in its string. Asked in the Onsite coding round 4 stage. If multiple strings tie, select all; return a string of the characters only present in the selected strings.

Output

1. One row per selected string, excluding NULL and empty strings.
2. Return selected_string, max_common_character_proportion, and exclusive_characters.
3. exclusive_characters must contain characters appearing in at least one selected string and no unselected string, sorted lexicographically and concatenated without separators.
4. Order by selected_string ascending.