56. Merge Intervals

Discussion Post (created on 24/11/2021 at 11:52)

56. Merge Intervals

Medium

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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.

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] overlaps, 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.

Constraints:

• 1 <= intervals.length <= 104

• intervals[i].length == 2

• 0 <= starti <= endi <= 104

class Solution:
    def merge(self, intervals: List[List[int]]) -> List[List[int]]:
        intervals.sort(key=lambda x : x[0])
        result = []
        for interval in intervals:
            if not result:
                result.append(interval)
                continue
            lastInterval = result[-1]
            thisTime = interval[0]
            lastTime = lastInterval[1]
            if thisTime <= lastTime:
                newInterval = [min(lastInterval[0], interval[0]), max(lastInterval[1], interval[1])]
                result.pop()
                result.append(newInterval)
            else:
                result.append(interval)
        return result