435. Non-overlapping Intervals
阿新 • • 發佈:2020-08-01
Given a collection of intervals, find the minimum number of intervals you need to remove to make the rest of the intervals non-overlapping.
Example 1:
Input: [[1,2],[2,3],[3,4],[1,3]] Output: 1 Explanation: [1,3] can be removed and the rest of intervals are non-overlapping.
Example 2:
Input: [[1,2],[1,2],[1,2]] Output: 2 Explanation: You need to remove two [1,2] to make the rest of intervals non-overlapping.
Example 3:
Input: [[1,2],[2,3]] Output: 0 Explanation: You don't need to remove any of the intervals since they're already non-overlapping.
Note:
- You may assume the interval's end point is always bigger than its start point.
- Intervals like [1,2] and [2,3] have borders "touching" but they don't overlap each other.
class Solution { public int eraseOverlapIntervals(int[][] intervals) { if(intervals.length == 0) return 0; Arrays.sort(intervals, (a, b) -> a[1] - b[1]); int res = 1; int curend = intervals[0][1]; for(int i = 1; i < intervals.length; i++) {if(curend <= intervals[i][0]) { res++; curend = intervals[i][1]; } } return intervals.length - res; } }
把問題轉化成:intervals中最多有多少個不重疊的array,然後用總數減去就是答案,和452.Minimum Number of Arrows to Burst Balloons,以及merge intervals挺像,前兩者都要先把陣列按end排序,這樣能為我們獲取更多的不重疊array