Kth Largest Element in a Stream

Design a class that tracks the k-th largest element in a stream of test scores.

Input: one operation per line —

• init k v1 v2 … — first line: initialize with k and the initial values (possibly none)
• add x — add a score and print the current k-th largest

Output: init prints null; each add prints the k-th largest after insertion. There are always at least k values when add is called.