[shaghayeghfar]

Learners, PR Template

Self checklist

• I have titled my PR with Region | Cohort | FirstName LastName | Sprint | Assignment Title
• My changes meet the requirements of the task
• I have tested my changes
• My changes follow the style guide

Task code

CYF-1183

[cjyuan]

Could you use complexity to explain how the new implementation is better than the original implementation?

[shaghayeghfar]

Dear @cjyuan
thank you for taking time and check my code, I really appreciate it .

about for question :

For count_letters, the original implementation checks whether each uppercase letter's lowercase version exists in the string. The in operation on a string takes O(n) time, so repeating it for each character gives O(n²) time complexity.

The new implementation uses sets to collect uppercase and lowercase letters in one pass, then checks membership in the lowercase set. Set lookups take O(1) on average, so the overall time complexity is O(n) on average.

Therefore, the new implementation improves the time complexity from O(n²) to O(n), making it more efficient for longer strings.

[cjyuan]

How about find_longest_common_prefix()? How much better is the new implementation compare to the original one?