Given a list of intervals, remove all intervals that are covered by another interval in the list.
Interval [a,b) is covered by interval [c,d) if and only if c <= a and b <= d.
After doing so, return the number of remaining intervals.
Example 1:
Input: intervals = [[1,4],[3,6],[2,8]] Output: 2 Explanation: Interval [3,6] is covered by [2,8], therefore it is removed.
Example 2:
Input: intervals = [[1,4],[2,3]] Output: 1
Example 3:
Input: intervals = [[0,10],[5,12]] Output: 2
Example 4:
Input: intervals = [[3,10],[4,10],[5,11]] Output: 2
Example 5:
Input: intervals = [[1,2],[1,4],[3,4]] Output: 1
Constraints:
1 <= intervals.length <= 1000intervals[i].length == 20 <= intervals[i][0] < intervals[i][1] <= 10^5- All the intervals are unique.