352. Data Stream as Disjoint Intervals

题目

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

For example, suppose the integers from the data stream are 1, 3, 7, 2, 6, ..., then the summary will be:

[1, 1]
[1, 1], [3, 3]
[1, 1], [3, 3], [7, 7]
[1, 3], [7, 7]
[1, 3], [6, 7]

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

Credits:Special thanks to @yunhong for adding this problem and creating most of the test cases.

解题思路

见程序注释