Problem

Given an array of intervals intervals where intervals[i] = [starti, endi], return the minimum number of intervals you need to remove to make the rest of the intervals non-overlapping.

Example 1:

1
2
3
4
Input: intervals = [[1,2],[2,3],[3,4],[1,3]]
Output: 1
Explanation: [1,3] can be removed and the rest of the intervals are non-overlapping.

Example 2:

1
2
3
4
Input: intervals = [[1,2],[1,2],[1,2]]
Output: 2
Explanation: You need to remove two [1,2] to make the rest of the intervals non-overlapping.

Example 3:

1
2
3
4
Input: intervals = [[1,2],[2,3]]
Output: 0
Explanation: You don't need to remove any of the intervals since they're already non-overlapping.

Constraints:

  • 1 <= intervals.length <= 10^5
  • intervals[i].length == 2
  • 5 * 10^4 <= starti < endi <= 5 * 10^4

Solve

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
class Solution:

def eraseOverlapIntervals(self, intervals: List[List[int]]) -> int:
if not intervals:
return 0

intervals.sort()

last_end = intervals[0][1]

res = 0

for i in range(1 , len(intervals )):
if intervals[i][0] >= last_end:
last_end = intervals[i][1]
else:
last_end = min(last_end , intervals[i][1])
res +=1
return res