Merge Overlapping Time Ranges

Merge Overlapping Time Ranges

You are given a list of time intervals, where each interval is represented as a list of two integers [start, end]. An interval [a, b] overlaps with [c, d] if there is any common point between them, including endpoints (e.g., [1, 3] and [3, 5] should be merged into [1, 5]).

Your task is to write a function that takes a list of intervals and returns a new list of intervals where all overlapping intervals have been merged into a single continuous range.

Function Signature

def merge_intervals(intervals: List[List[int]]) -> List[List[int]]:

Constraints

• 1 <= intervals.length <= 10,000
• 0 <= start < end <= 10^9

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, they are merged into [1, 6].

Example 2: Input: [[1, 4], [4, 5]] Output: [[1, 5]] Explanation: Since the end of the first interval matches the start of the second, they are merged.

Edge Cases

• A list containing a single interval.
• Intervals that are completely contained within others (e.g., [[1, 10], [2, 5]]).
• Unsorted input lists.