Intervals - Remove Covered Intervals

Given a list of intervals, remove all intervals covered by another interval. An interval [a,b] is covered by [c,d] if c <= a and b <= d. Return the number of remaining intervals.

Input: [[1,4],[3,6],[2,8]] → Output: 2

Input: [[1,4],[2,3]] → Output: 1

Sort by start ascending, then by end descending (so for equal starts, longer interval comes first). Keep track of the maximum end seen so far. If current end <= maxEnd, current interval is covered.

Sort: by start asc, then end desc.
Track maxEnd = 0, count = 0.
For each interval: if end > maxEnd, count++, maxEnd = end (not covered).
Return count.

import java.util.*; class Solution { public int removeCoveredIntervals(int[][] intervals) { Arrays.sort(intervals, (a,b) -> a[0] != b[0] ? a[0]-b[0] : b[1]-a[1]); int count = 0, maxEnd = 0; for (int[] iv : intervals) { if (iv[1] > maxEnd) { count++; maxEnd = iv[1]; } } return count; } }

Time Complexity: O(N log N)
Space Complexity: O(1)