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).