Data Stream as Disjoint Intervals

Given a data stream input of non-negative integers a1, a2, ..., an, summarize the numbers seen so far as a list of disjoint intervals.

Implement the SummaryRanges class:

  • SummaryRanges() Initializes the object with an empty stream.
  • void addNum(int val) Adds the integer val to the stream.
  • int[][] getIntervals() Returns a summary of the integers in the stream currently as a list of disjoint intervals [starti, endi].

 

Example 1:

Input
["SummaryRanges", "addNum", "getIntervals", "addNum", "getIntervals", "addNum", "getIntervals", "addNum", "getIntervals", "addNum", "getIntervals"]
[[], [1], [], [3], [], [7], [], [2], [], [6], []]
Output
[null, null, [[1, 1]], null, [[1, 1], [3, 3]], null, [[1, 1], [3, 3], [7, 7]], null, [[1, 3], [7, 7]], null, [[1, 3], [6, 7]]]

Explanation
SummaryRanges summaryRanges = new SummaryRanges();
summaryRanges.addNum(1);      // arr = [1]
summaryRanges.getIntervals(); // return [[1, 1]]
summaryRanges.addNum(3);      // arr = [1, 3]
summaryRanges.getIntervals(); // return [[1, 1], [3, 3]]
summaryRanges.addNum(7);      // arr = [1, 3, 7]
summaryRanges.getIntervals(); // return [[1, 1], [3, 3], [7, 7]]
summaryRanges.addNum(2);      // arr = [1, 2, 3, 7]
summaryRanges.getIntervals(); // return [[1, 3], [7, 7]]
summaryRanges.addNum(6);      // arr = [1, 2, 3, 6, 7]
summaryRanges.getIntervals(); // return [[1, 3], [6, 7]]

 

Constraints:

  • 0 <= val <= 104
  • At most 3 * 104 calls will be made to addNum and getIntervals.

 

Follow up: What if there are lots of merges and the number of disjoint intervals is small compared to the size of the data stream?

SOLUTION:
import bisect

class SummaryRanges:

    def __init__(self):
        self.nums = []
        self.dup = set()

    def addNum(self, val: int) -> None:
        if val not in self.dup:
            bisect.insort(self.nums, val)
            self.dup.add(val)

    def getIntervals(self) -> List[List[int]]:
        nums = self.nums
        n = len(nums)
        if n == 0:
            return []
        ranges = [[nums[0]]]
        for i in range(1, n):
            if nums[i] == ranges[-1][-1] or nums[i] == ranges[-1][-1] + 1:
                ranges[-1].append(nums[i])
            else:
                ranges.append([nums[i]])
        return [[r[0], r[-1]] for r in ranges]


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

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