Design a data structure to find streaming median

### Problem Design a data structure that supports maintaining the **median** of a stream of integers. Implement a class/ADT with the following operations: - `addNum(x)`: Add an integer `x` to the data structure. - `findMedian()`: Return the median of all numbers added so far. ### Median definition - If the count `n` is odd, the median is the middle element after sorting. - If `n` is even, the median is the average of the two middle elements (return a floating-point number if needed). ### Constraints / expectations - The stream can be very large. - Values may include negatives and duplicates. - Aim for efficient per-operation time (better than sorting on every query). ### Follow-up If the input stream is **extremely large** and contains **many repeated values**, how would you optimize the design (time and/or memory)?