Solve three easy algorithm problems

You are given three independent algorithmic tasks. For each one, explain your approach (no need to run code). ## 1) Merge two sorted lists (integers instead of nodes) Given two sorted integer arrays `A` and `B` (non-decreasing order), merge them into a single sorted array containing all elements from both inputs. - **Input:** two arrays `A`, `B` - **Output:** merged sorted array - **Constraints (typical):** `0 <= len(A), len(B) <= 1e5` ## 2) Max profit from one stock transaction Given an array `prices` where `prices[i]` is the stock price on day `i`, compute the maximum profit you can achieve by choosing **at most one** day to buy and a later day to sell. If no profit is possible, return `0`. - **Input:** array `prices` - **Output:** integer max profit - **Constraints (typical):** `1 <= n <= 1e5`, `0 <= prices[i] <= 1e9` ## 3) Validate parentheses pairing Given a string `s` consisting only of the characters `'('`, `')'`, `'['`, `']'`, `'{'`, `'}'`, determine whether the parentheses/brackets are **valid**. A string is valid if: - Every opening bracket has a corresponding closing bracket of the same type. - Brackets are closed in the correct order. - **Input:** string `s` - **Output:** boolean - **Constraints (typical):** `0 <= |s| <= 1e5`