Implement palindrome check and valid parentheses

You have **20–25 minutes per problem**. Implement the following two functions and be prepared to explain your approach and **time/space complexity**. ## Problem 1 — Palindrome Check Write a function that determines whether a given string is a palindrome. - A string is a palindrome if it reads the same forward and backward. - Compare characters **exactly as they appear** (no case folding and no ignoring punctuation/whitespace unless you explicitly state and implement it). **Function signature (example):** - `bool is_palindrome(s: str)` **Input:** - `s`: a string (may be empty) **Output:** - `true` if `s` is a palindrome, otherwise `false` **Examples:** - `"abba" -> true` - `"abc" -> false` - `"" -> true` ## Problem 2 — Valid Parentheses Sequence Write a function that checks whether a string containing only parentheses characters is valid. A string is **valid** if: 1. Every opening bracket has a corresponding closing bracket of the same type. 2. Brackets close in the correct order. Assume the allowed bracket types are: `()`, `[]`, `{}`. **Function signature (example):** - `bool is_valid_parentheses(s: str)` **Input:** - `s`: a string consisting only of characters in `()[]{} ` (may be empty) **Output:** - `true` if `s` is valid, otherwise `false` **Examples:** - `"()" -> true` - `"([]){}" -> true` - `"(]" -> false` - `"([)]" -> false` - `"" -> true` ## Documentation requirement For each function, include a docstring with: - **Description** - **Inputs/Outputs** - **Callouts** (assumptions, edge cases, complexity)