Answer two coding questions (SQL and DP)

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