Design a data structure that supports insert, delete, and getRandom operations, all in average O(1) time. The getRandom method should return a random element from the current set of elements.

You are given an array representing the heights of vertical lines. Find two lines that, together with the x-axis, form a container that holds the most water.

You are given a list of meeting time intervals. Determine the minimum number of conference rooms required to accommodate all the meetings without any overlap.