
Longest Substring of Unique Characters

Given a string, find the length of the longest substring without repeating characters.
Input: String (str).
Output: Integer (int).
Examples:
assert longest_substr("abcabcbb") == 3 assert longest_substr("bbbbb") == 1 assert longest_substr("pwwkew") == 3 assert longest_substr("abcdef") == 6
How it’s used:
- data validation for passwords to ensure the inclusion of a sufficiently long sequence of non-repeated characters;
- text analysis, especially for cryptography and coding patterns;
- identifying unique patterns in a sequence.