You are given three small programming tasks (typical “easy” difficulty). Implement each as a function. ## Task 1: Validate parentheses Given a string `s` consisting only of the characters `'(' , ')' , '{' , '}' , '[' , ']'`, determine whether it is valid. A string is valid if: - Open brackets are closed by the same type of brackets. - Open brackets are closed in the correct order. - Every close bracket has a corresponding open bracket. **Input:** `s` (length `0…1e5`) **Output:** `true` if valid, else `false` ## Task 2: Longest substring without repeating characters Given a string `s` (ASCII), return the length of the longest substring that contains no repeated characters. **Input:** `s` (length `0…2e5`) **Output:** integer length ## Task 3: Fetch from a public GET API and transform You are given a public HTTP GET endpoint that returns JSON. Assume the endpoint returns an array of records in the form: ```json [ {"id":"a1","group":"books","amount":12,"ts":"2026-01-01T10:00:00Z"}, {"id":"a2","group":"books","amount":7,"ts":"2026-01-01T11:00:00Z"}, {"id":"b1","group":"games","amount":20,"ts":"2026-01-02T09:00:00Z"} ] ``` Write code that: 1. Calls the endpoint. 2. Parses the JSON. 3. Produces a summary per `group` with: - `count` of records - `totalAmount` (sum of `amount`) 4. Returns the summary list sorted by `group` ascending. **Constraints/notes:** - Records may be empty. - `amount` is a non-negative integer. - You may assume the response fits in memory (≤ `1e5` records). - Focus on correctness and clean error handling (HTTP errors, invalid JSON).