Problem

In Providence messaging and note-entry surfaces, repeated characters can appear in free-text input. Write a function that returns the length of the longest substring in a string s that contains no repeated characters.

Formal Specification

• Input: a string s
• Output: an integer representing the maximum length of any contiguous substring of s with all unique characters

A substring must be contiguous. The function should run efficiently for large inputs.

Examples

Example 1

• Input: s = "abcabcbb"
• Output: 3
• Explanation: The longest substring without repeating characters is "abc", which has length 3.

Example 2

• Input: s = "bbbbb"
• Output: 1
• Explanation: Every substring longer than one character repeats "b", so the best answer is 1.

Example 3

• Input: s = "pwwkew"
• Output: 3
• Explanation: "wke" is a valid longest substring. "pwke" is not valid because it is not contiguous.

Constraints

• 0 <= len(s) <= 10^5
• s may contain letters, digits, symbols, and spaces
• Return the length only, not the substring itself