Leetcode: 295. Find Median from Data Stream

Pattern: Answer query on sorted data. Keep a sorted list of the numbers and compute the median using it. Time complexity is \(O(n \log n)\) and space is \(O(n)\).

from sortedcontainers import SortedList


class MedianFinder:
    def __init__(self):
        self.s = SortedList()

    def addNum(self, num: int) -> None:
        self.s.add(num)

    def findMedian(self) -> float:
        N = len(self.s)
        if N % 2 == 0:
            return (self.s[N // 2] + self.s[N // 2 - 1]) / 2
        return self.s[N // 2]


# Your MedianFinder object will be instantiated and called as such:
# obj = MedianFinder()
# obj.addNum(num)
# param_2 = obj.findMedian()