merge_intervals.py

class Solution:
    def merge(self, intervals: List[List[int]]) -> List[List[int]]:
        intervals.sort(key= lambda x:x[0])
        output=[intervals[0]]
        for start,end in intervals[1:]:
            lastEnd=output[-1][1]
            if start<=lastEnd:
                output[-1][1]=max(lastEnd,end)
            else:
                output.append([start,end])
        return output