diff --git a/Sprint-2/improve_with_precomputing/common_prefix/common_prefix.py b/Sprint-2/improve_with_precomputing/common_prefix/common_prefix.py index f4839e7..96b633e 100644 --- a/Sprint-2/improve_with_precomputing/common_prefix/common_prefix.py +++ b/Sprint-2/improve_with_precomputing/common_prefix/common_prefix.py @@ -1,18 +1,26 @@ from typing import List -def find_longest_common_prefix(strings: List[str]): +def find_longest_common_prefix(strings: List[str]) -> str: """ find_longest_common_prefix returns the longest string common at the start of any two strings in the passed list. In the event that an empty list, a list containing one string, or a list of strings with no common prefixes is passed, the empty string will be returned. """ + if len(strings) < 2: + return "" + + # PRE-COMPUTE by sorting strings once + strings = sorted(strings) + longest = "" - for string_index, string in enumerate(strings): - for other_string in strings[string_index+1:]: - common = find_common_prefix(string, other_string) - if len(common) > len(longest): - longest = common + + #compare only strings that are next to eacotherr in sorted order + for i in range(len(strings) - 1): + common = find_common_prefix(strings[i], strings[i + 1]) + if len(common) > len(longest): + longest = common + return longest