Package g0201_0300.s0295_find_median_from_data_stream

Class MedianFinder

  • All Implemented Interfaces:
    
public final class MedianFinder

    295 - Find Median from Data Stream.

    Hard

    The median is the middle value in an ordered integer list. If the size of the list is even, there is no middle value and the median is the mean of the two middle values.

    • For example, for arr = [2,3,4], the median is 3.

    • For example, for arr = [2,3], the median is (2 + 3) / 2 = 2.5.

    Implement the MedianFinder class:

    • MedianFinder() initializes the MedianFinder object.

    • void addNum(int num) adds the integer num from the data stream to the data structure.

    • double findMedian() returns the median of all elements so far. Answers within <code>10<sup>-5</sup></code> of the actual answer will be accepted.

    Example 1:

    Input

    ["MedianFinder", "addNum", "addNum", "findMedian", "addNum", "findMedian"]
[ [], [1], [2], [], [3], []]

    Output: null, null, null, 1.5, null, 2.0

    Explanation:

    MedianFinder medianFinder = new MedianFinder();
medianFinder.addNum(1); // arr = [1]
medianFinder.addNum(2); // arr = [1, 2]
medianFinder.findMedian(); // return 1.5 (i.e., (1 + 2) / 2)
medianFinder.addNum(3); // arr[1, 2, 3]
medianFinder.findMedian(); // return 2.0

    Constraints:

    • <code>-10<sup>5</sup><= num <= 10<sup>5</sup></code>

    • There will be at least one element in the data structure before calling findMedian.

    • At most <code>5 * 10<sup>4</sup></code> calls will be made to addNum and findMedian.

    Follow up:

    • If all integer numbers from the stream are in the range [0, 100], how would you optimize your solution?

    • If 99% of all integer numbers from the stream are in the range [0, 100], how would you optimize your solution?

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description

    • Field Summary

      Fields 
      Modifier and Type Field Description

    • Constructor Summary

      Constructors 
      Constructor Description
      MedianFinder()

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description