HashedIn Interview Experience for Intern+FTE (On-Campus)

HashedIn Interview Experience for Intern+FTE (On-Campus)
HashedIn Technologies visited our campus in November 2020(virtually). They conducted 4 rounds of interview.
Round 1 (Coding Test): This round was held on their own platform. The test was proctored and consisted of 3 questions. The duration of the test was 60 minutes.
Modification of https://www.geeksforgeeks.org/count-distinct-subsequences/
It was a dynamic programming question that I can’t remember exactly.
We needed to write the code/algorithm in a simple text area and explain the approach. There was no option to run the code. I was able to solve two questions with an optimized solution and one with a naïve approach.
Out of 40 students who applied only 6 students were selected for the interview rounds.
Round 2 (Technical Interview -1): The interview started with a basic introduction. They asked few questions based on the projects and internships which I did. Then they shared a google doc where I was supposed to write my responses.They asked me questions based on programming and DSA. A few of them are:
Find the row which had maximum numbers of 1s in a matrix of 0s and 1s.
Sort the array consisting of 0s and 1s.
Find the missing number from the array of natural numbers.
Other questions in the interview revolved around the responses which I gave.
The duration of this interview was about 1 hour. 
Round 3(Technical Interview -2): The interviewer was very straightforward, without any introduction, the round started with a MySQL question. The question was based on joins, and I was supposed to write the query for the same.
A few DS related questions which were asked are:
Find the distance between two leaf nodes in a binary tree.
He gave me an input array – [3 4 5 2 2 5 2 4] and an output array- [3 4 4 5 5 2 2 2 ] . The interviewer expected me to observe the pattern and write the code of the function which when takes the given input array and returns the output as shown.
He gave me some data and asked me to map it to a suitable data structure which I solved using hash maps.
He gave me some data and asked me to code for the dummy application completely by following all the OOPS concepts. I coded it all in C++ and explained the approach as well.
There are 100 different types of caps each having a unique id from 1 to 100. Also, there are ‘n’ persons each having a collection of a variable number of caps. One day all of these persons decide to go to a party wearing a cap but to look unique they decided that none of them will wear the same type of cap. So, count the total number of arrangements or ways such that none of them is wearing the same type of cap. Constraints: 1