Merge Intervals 218

Given an array of `intervals` where `intervals[i] = [start_i, end_i]`, merge all overlapping intervals, and return *an array of the non-overlapping intervals that cover all the intervals in the input*. ## Example 1: ``` Input: intervals = [[1,3],[2,6],[8,10],[15,18]] Output: [[1,6],[8,10],[15,18]] Explanation: Since intervals [1,3] and [2,6] overlap, merge them into [1,6]. ``` ## Example 2: ``` Input: intervals = [[1,4],[4,5]] Output: [[1,5]] Explanation: Intervals [1,4] and [4,5] are considered overlapping. ``` ## Constraints: - `1 <= intervals.length <= 10^4` - `intervals[i].length == 2` - `0 <= start_i <= end_i <= 10^4`