352. Data Stream as Disjoint Intervals
Hard
1.6K
343

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 value)` Adds the integer `value` to the stream.
• `int[][] getIntervals()` Returns a summary of the integers in the stream currently as a list of disjoint intervals `[starti, endi]`. The answer should be sorted by `starti`.

Example 1:

```Input
[[], [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.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 <= value <= 104`
• At most `3 * 104` calls will be made to `addNum` and `getIntervals`.
• At most `102` calls will be made to `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?

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