#Dsa

Solve the LeetCode problem of finding the length of the longest valid parentheses substring.

Solve the LeetCode problem of finding the least number of unique integers remaining after performing K removals.

Given a list, find all duplicate elements within it. Provide an algorithm that is efficient in terms of time and space complexity.

Given an array, reverse the elements from both sides starting from a specified index. For example, given `arr = [1,2,3,4,5]` and `ind = 2`, return `Array = [3,2,1,5,4]`. Explain your approach and any key considerations.