could you please provide me with some hints regarding this question which I could use to solve this question?
Hints required for logic formation
Iterate through the array which contains stream of numbers.
To keep track of top k elements, make a top vector of size k+1.
For every element in the stream increase its frequency and store it in the last position of top vector. We can use hashing for efficiently fetching frequency of an element and increasing it.
Now find the position of element in top vector and iterate from that position to zero. For finding position we can make use of the find() function in C++ STL, it returns an iterator pointing to element if found in the vector.
And make that list of k+1 numbers sorted according to frequency and their value.
Print top k elements form top vector.
Repeat the above steps for every element in the stream.