1. Given an array of 0's and 1's, how many 0's needed to be flipped consecutively to make maximum 1s. 2. Given two API details, one having company wise stock prices and one holdings, calculate the total asset value on a particular date. The APIs were of two kind- one paginated and one returning all in one go. It was required to implement a runnable code with Rest Call logic accessing APIs and calculating the total asset value on a particular day. Face to Face round: 1. What is Observer design Pattern? 2. How would you approach towards optimizing the performance of an on-premise Java Server. 3. Double checked locking. 4. Need of immutable classes. Last round: Write unit test case of the hackerrank test question 1.