Merge Intervals

Given an array of intervals where each interval is [start, end], merge all overlapping intervals, and return an array of the non-overlapping intervals that cover all the intervals in the input. Input A 2D array intervals, where intervals[i] = [start_i, end_i]. Output A 2D array representing the merged intervals. Example Input: intervals = [[1,3],[2,6],[8,10],[15,18]] Output: [[1,6],[8,10],[15,18]] Input: intervals = [[1,4],[4,5]] Output: [[1,5]] Constraints intervals[i][0] <= intervals[i][1] The number of intervals is in the range [1, 10^4]. Complexity Expected time complexity: O(n log n), where n is the number of intervals Expected space complexity: O(n) Example Input [[1,3],[2,6],[8,10],[15,18]]