思路其实不难,排序后模拟就好了,不太能理解为啥get(0)后,对intervals遍历temp是从get(1)元素开始的。如果一个集合中get了一个元素,那这个元素还不在集合中吗?这个点比较困惑。
import java.util.*; /** * Definition for an interval. * public class Interval { * int start; * int end; * Interval() { start = 0; end = 0; } * Interval(int s, int e) { start = s; end = e; } * } */ public class Solution { public ArrayList<Interval> merge(ArrayList<Interval> intervals) { ArrayList<Interval> res=new ArrayList<Interval>(); if(intervals.size()==0||intervals==null) return res; Collections.sort(intervals,(a,b)->a.start-b.start); int newStart=intervals.get(0).start; int newEnd=intervals.get(0).end; for(Interval interval :intervals){ if(interval.start<=newEnd&&interval.end>newEnd) newEnd=interval.end; if(interval.start>newEnd){ res.add(new Interval(newStart,newEnd)); newStart=interval.start; newEnd=interval.end; } } res.add(new Interval(newStart,newEnd)); return res; } }