Solve the following two string problems. ## Problem 1 — Longest substring with all distinct characters Given a string `s`, find the **length** of the longest contiguous substring that contains **no repeated characters**. - **Input:** `s` (ASCII or Unicode string) - **Output:** an integer length - **Constraints (typical):** `0 ≤ |s| ≤ 10^5` Example: - `s = "abcabcbb"` → output `3` (substring could be `"abc"`) ## Problem 2 — First unique character Given a string `s`, return the **index (0-based)** of the first character that appears **exactly once** in the entire string. If no such character exists, return `-1`. - **Input:** `s` - **Output:** integer index or `-1` - **Constraints (typical):** `0 ≤ |s| ≤ 10^5` Example: - `s = "leetcode"` → output `0` - `s = "aabb"` → output `-1`