merge_intervals.py

class Solution:
    def merge(self, intervals: List[List[int]]) -> List[List[int]]:
        if not intervals :
            return []
        ans = []
        intervals.sort(key = lambda x :x[0])
        for interval in intervals :
            if not ans or interval[0] > ans[-1][1] :
                ans.append(interval)
            else:
                ans[-1][1] = max(ans[-1][1],interval[1])
            
        return ans