It seems a little easy to use sort and find the start and end of the interval until no cover.
Yes accept! We need to think about three situation, {} represent the new interval [] original interval
- {[]} continue
- {[}] record left
- [{]} record right
As for [{}] it must satisfy both 2 and 3, becuase [ < } and ] > }
Thus we can reduce all these into a interval. And then we insert it into the answer.