class Solution:
def merge(self, intervals: List[List[int]]) -> List[List[int]]:
intervals.sort(key = lambda x:x[0])
res = []
res.append(intervals[0])
for i in range(1,len(intervals)):
if res[-1][1]>= intervals[i][0]:
res[-1][1] = max(res[-1][1],intervals[i][1])
else:
res.append(intervals[i])
return res