Merge overlapping intervals

Problem Statement

Given a collection of intervals, merge all overlapping intervals and return an array of the non-overlapping intervals that cover all the intervals in the input.

An interval is defined as [start, end]. Two intervals [a, b] and [c, d] overlap if c List[List[int]]:

Examples

Example 1: Input: [[1, 3], [2, 6], [8, 10], [15, 18]] Output: [[1, 6], [8, 10], [15, 18]] Explanation: Since [1, 3] and [2, 6] overlap, merge them into [1, 6].

Example 2: Input: [[1, 4], [4, 5]] Output: [[1, 5]] Explanation: Intervals [1, 4] and [4, 5] are considered overlapping because they touch at 4.

Constraints

• 1 <= intervals.length <= 10^4
• 0 <= start_i <= end_i <= 10^4

Edge Cases to Consider

• Empty input list.
• A list containing a single interval.
• Intervals that are completely nested inside others (e.g., [[1, 10], [2, 3]]).
• Intervals that are identical.