Merge Intervals (LeetCode 56)

Given a list of intervals, merge every overlapping interval and return the non-overlapping coverage. Examples Example 1: Input: intervals = [[1,3],[1,5],[6,7]] Output: [[1,5],[6,7]] Example 2: Input: intervals = [[1,2],[2,3]] Output: [[1,3]] Constraints 1 <= intervals.length <= 1000 intervals[i].length == 2 0 <= start <= end <= 1000