Given a collection of intervals where each interval is a pair [start, end], merge all overlapping intervals and return the result.
For example, given [[1,3],[2,6],[8,10],[15,18]], the merged result is [[1,6],[8,10],[15,18]] because [1,3] and [2,6] overlap.
Explain your approach step by step and analyze the time and space complexity.
How to approach it
- Hint 1
What happens if you sort the intervals by their start time first?
- Hint 2
After sorting, two consecutive intervals overlap if the current interval's start is less than or equal to the previous interval's end.
- Hint 3
When intervals overlap, merge them by extending the end to the maximum of both ends.
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