SDE - 2

Ninja is observing an array of ‘N’ numbers and wants to make as many unique subsets as possible. Can you help the Ninja to find all the unique subsets?

Note: Two subsets are called same if they have same set of elements.For example {3,4,1} and {1,4,3} are not unique subsets.

You are given an array ‘ARR’ having N elements. Your task is to print all unique subsets.

For Example

For the given if ARR = [1,1,3],the answer will be [ ],[1],[1,1],[1,3],[3],[1,1,3].

There are 'N' houses on the left side of the road and 'N' houses on the right side. All of these houses are coloured. The colour of houses on the left and right sides is given by arrays 'A' and 'B', respectively.

Both the arrays 'A' and 'B' are permutations of length 'N'. A permutation of length 'N' is the sequence of length 'N', which consists of all the integers from 1 to 'N' exactly once.

For an 'i-th' house on the left side, you are supposed to find the house on the right side with the same colour as 'A[i]'.

Example :

'N' = 3, 'A' = {1, 2, 3}, 'B' = {2, 3, 1}.

House 1 on the left side has the same colour as house 3 on the right side.
House 2 on the left side has the same colour as house 1 on the right side.
House 3 on the left side has the same colour as house 2 on the right side.

The answer is {3, 1, 2}.

Implement an in-memory Twitter system with features to Follow/Unfollow users, post Tweets, and retrieve the last N tweets of a user and their followed accounts. Include functionality to delete tweets and maintain user-specific timelines, ensuring efficient updates and retrievals using data structures like hashmaps and priority queues.