## DEV Community

Abhishek Chaudhary

Posted on

# Remove Covered Intervals

Given an array `intervals` where `intervals[i] = [li, ri]` represent the interval `[li, ri)`, remove all intervals that are covered by another interval in the list.

The interval `[a, b)` is covered by the interval `[c, d)` if and only if `c <= a` and `b <= d`.

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

Constraints:

• `1 <= intervals.length <= 1000`
• `intervals[i].length == 2`
• `0 <= li < ri <= 105`
• All the given intervals are unique.

SOLUTION:

``````import bisect

class Solution:
def removeCoveredIntervals(self, intervals: List[List[int]]) -> int:
intervals.sort(key = lambda p: (p[0], p[0] - p[1]))
n = len(intervals)
i = 0
while i < len(intervals):
a, b = intervals[i]
j = i + 1
while j < len(intervals) and intervals[j][0] <= b:
c, d = intervals[j]
if d <= b:
intervals.pop(j)
else:
j += 1
i += 1
return len(intervals)
``````