Merge_Intervals.py

class Solution:
    def merge(self, intervals: List[List[int]]) -> List[List[int]]:
        intervals.sort(key=lambda i :i[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