Find longest substring without repeating characters

Problem

Given a string s, find the length of the longest contiguous substring that contains no repeated characters.

Input

• A string s (may contain letters, digits, symbols, and spaces).

Output

• An integer: the maximum length among all substrings of s that have all unique characters.

Examples

1. s = "abcabcbb" → output 3 (e.g., "abc")
2. s = "bbbbb" → output 1 (e.g., "b")
3. s = "pwwkew" → output 3 (e.g., "wke")

Constraints (typical interview assumptions)

• 0 ≤ len(s) ≤ 10^5
• Aim for an algorithm faster than O(n^2).

Notes

• Substring must be contiguous (not a subsequence).