#Algorithms

Write a C# method that returns the second highest distinct number in an integer array. Input: `[10, 5, 20, 8, 20]` Output: `10` (since 20 is the highest and 10 is the next distinct value)

Given a list of integers, find all unique pairs whose sum is equal to 10. Once an element is used in a pair, it cannot be reused. Optimize your solution for time and space complexity.

Questions focusing on Dynamic Programming algorithms and techniques.

Write a Java program to generate and print all permutations of a given string.

Tackle a dynamic programming problem that requires optimal solutions.