Merge intervals

merge_intervals.py

class Solution:
    def merge(self, intervals: List[List[int]]) -> List[List[int]]:
        if len(intervals) < 2:
            return intervals
        res = []
        for pair in sorted(intervals, key = lambda p:p[0]):
            if res and res[-1][1] >= pair[0]:
                res[-1][1] = max(res[-1][1], pair[1])
            else:
                res.extend([pair])
        return res