Merge Intervals

Problem Given intervals [start, end], merge all overlapping ones and return the disjoint set covering the input.

Input / Output

• Input: int[][] intervals. Output: merged non-overlapping intervals.

Constraints

• Up to 10^4 intervals; O(n log n) from the sort dominates.

Example

• [[1,3],[2,6],[8,10],[15,18]] → [[1,6],[8,10],[15,18]]; touching intervals [1,4],[4,5] merge → [1,5].