Problem URL: Data stream as disjoint intervals

We will construct the interval by expanding around each of the added numbers.

class SummaryRanges:
    def __init__(self):
        self.nums = set()

    def addNum(self, value: int) -> None:
        self.nums.add(value)

    def getIntervals(self) -> List[List[int]]:
        intervals = []
        seen = set()
        for num in self.nums:
            if num in seen: 
                continue

            left = num
            while left - 1 in self.nums:
                left -= 1
                seen.add(left)

            right = num
            while right + 1 in self.nums:
                right += 1
                seen.add(right)

            intervals.append([left, right])

        return sorted(intervals)

# Your SummaryRanges object will be instantiated and called as such:
# obj = SummaryRanges()
# obj.addNum(value)
# param_2 = obj.getIntervals()

Time complexity: O(n) for getIntervals, O(1) for addNum
Space complexity: O(n)