Merge intervals

hardSorting and searching40 XP

Each interval is [start, end]. Merge all intervals that overlap or touch, and return the result sorted by start.

Examples

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]]

Examples use JSON: true/false/null are True/False/None in Python.