56. Merge Intervals

Given an array of intervals where intervals[i] = [starti, endi], merge all overlapping intervals, and return an array of the non-overlapping intervals that cover all the intervals in the input

Array Sorting Quicksort

Example 1:

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

Example 2:

Input: intervals = [[1,4],[4,5]]
Output: [[1,5]]
Explanation: Intervals [1,4] and [4,5] are considered overlapping.

Example 3:

Input: intervals = [[4,7],[1,4]]
Output: [[1,7]]
Explanation: Intervals [1,4] and [4,7] are considered overlapping.

Constraints:

1 <= intervals.length <= 10^4
intervals[i].length == 2
0 <= starti <= endi <= 10^4

Solution

class Solution:
    def merge(self, intervals: list[list[int]]) -> list[list[int]]:
        intervals.sort(key=lambda x: x[0])
        result = []

        for start, end in intervals:
            if result and start <= result[-1][1]:
                result[-1][1] = max(result[-1][1], end)
            else:
                result.append([start, end])

        return result