435. Non-overlapping Intervals
Đề Bài
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:
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:
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:
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 <= 105intervals[i].length == 2-5 * 104 <= starti < endi <= 5 * 104
Thuật Toán & Kỹ Thuật
⏱️ Thời gian
O(n log n)
💾 Không gian
O(n)
Lời Giải
Python
0435-non-overlapping-intervals.py
class Solution:
def eraseOverlapIntervals(self, intervals: List[List[int]]) -> int:
intervals.sort(key = lambda x: x[1])
prev, cnt = -inf, 0
for start, end in intervals:
if start >= prev:
prev = end
else:
cnt += 1
return cnt
# [1, 2], [1, 3], [2, 3], [3, 4]