Remove_Covered_Intervals.py

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

#My Solution
# O(n^2) Time and O(1) Space
class Solution:
    def removeCoveredIntervals(self, intervals: List[List[int]]) -> int:
        
        result = len(intervals)
        for i in range(len(intervals)):
            for j in range(len(intervals)):
                
                if intervals[i][0] >= intervals[j][0] and intervals[i][1] <= intervals[j][1] and i!=j:
                    
                    result -= 1
                    break
        
        return result


# O(nlogn) Time and O(1) Space
class Solution:
    def removeCoveredIntervals(self, intervals: List[List[int]]) -> int:
        
        result = len(intervals)
        intervals.sort()
        start, end = intervals[0]
        # print(intervals)
        # print(start, end)
        for i in range(1, len(intervals)):
            if start<=intervals[i][0] and end>=intervals[i][1]:
                result -= 1
                
            else:
                if start == intervals[i][0]:
                    result -= 1
                    end = intervals[i][1]
                    
                else:
                    start, end = intervals[i]
        
        return result