Problem Statement

Given a word, write a function to generate all of its unique generalized abbreviations.

A generalized abbreviation of a word can be generated by replacing each substring of the word with the count of characters in the substring. Take the example of “ab” which has four substrings: “”, “a”, “b”, and “ab”. After replacing these substrings in the actual word by the count of characters, we get all the generalized abbreviations: “ab”, “1b”, “a1”, and “2”.

Note: All contiguous characters should be considered one substring, e.g., we can’t take “a” and “b” as substrings to get “11”; since “a” and “b” are contiguous, we should consider them together as one substring to get an abbreviation “2”.

Example 1:

Input: "BAT"
Output: "BAT", "BA1", "B1T", "B2", "1AT", "1A1", "2T", "3"

Example 2:

Input: "code"
Output: "code", "cod1", "co1e", "co2", "c1de", "c1d1", "c2e", "c3", "1ode", "1od1", "1o1e", "1o2", "2de", "2d1", "3e", "4"

Constraints:

• 1 <= word.length <= 15
• word consists of only lowercase English letters.