Count the number of 0s, 1s and 2s in the given array. Then store all the 0s in the beginning followed by all the 1s then all the 2s.

I tried it with a min-heap and insert all lengths into the min-heap. Extract the minimum and second minimum from min-heap. Add the above two extracted values and insert the added value to the min-heap. Maintain a variable for total cost and keep incrementing it by the sum of extracted values. Return the value of this total cost

I had already solved this question so i have pretty much good idea about the question.
So first,i tried to solving by storing the sum at every step in hashmap. Which was not time and space efficent.
then I solved this question by the Kadane’s algorithm.

in this i have caluclated the height of left side tree then height of right side tree and added the result and returned the values in recursion. I have created one height function,and then call the function (left_height + right_height + 1) for each node and update the result.

Tip 1 : In this interviewer was trying to understand how depth knowledge i have on the system which i am currently working on.
Tip 2 : Understand the high level design of the system , how data follow and data store works.