352 - Data Stream as Disjoint Intervals\.

Hard

Given a data stream input of non-negative integers <code>a₁, a₂, ..., a_n</code>, 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 <code>start_i, end_i</code>.

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:

• <code>0 <= val <= 10⁴</code>

• At most <code>3 * 10⁴</code> 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?