Answer two coding questions (SQL and DP)
Company: Amazon
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Technical Screen
Solve the following two coding tasks.
## Problem A (SQL)
You are given a table:
**Employee(id INT, salary INT)**
Write a query that returns the **second highest distinct salary** in the company.
- If there is no second distinct salary, return `NULL`.
## Problem B (Dynamic Programming on strings)
Given a string `s` (lowercase English letters), compute the **number of distinct non-empty palindromic subsequences** of `s`.
Requirements:
- Return the count modulo `1_000_000_007`.
- Subsequences are formed by deleting zero or more characters without reordering.
- Two subsequences are considered different if their resulting strings differ.
Constraints (typical):
- `1 <= len(s) <= 1000`
Quick Answer: This multi-part question evaluates SQL query skills (handling distinct values, aggregation and edge-case NULL results) and algorithmic proficiency in dynamic programming on strings, specifically counting distinct palindromic subsequences under modular arithmetic.
