leetcode-15双周赛-1288-删除被覆盖区间

题目描述：

方法一：排序O(Nlogn）

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