一、题目内容

image.png

二、题解

解法1：

思路

区间左起点排序，然后模拟合并

代码

  1. public class Solution {
  2.     public ArrayList<Interval> merge(ArrayList<Interval> intervals) {
  3.         ArrayList<Interval> ans = new ArrayList<Interval>();
  4.         if(intervals == null || intervals.isEmpty()){
  5.             return ans;
  6.         }
  7.         if(intervals.size() == 1){
  8.             return intervals;
  9.         }
  10.         Collections.sort(intervals,(a,b)->a.start-b.start);
  11.         int left = 0,right = 1;
  12.         Interval curInterVal = intervals.get(left);
  13.         while(right<intervals.size()){
  14.             Interval rightInterval = intervals.get(right);
  15.             if(canMerge(curInterVal,rightInterval)){
  16.                 curInterVal = mergeInterval(curInterVal,rightInterval);
  17.                 right++;
  18.             }else{
  19.                 ans.add(curInterVal);
  20.                 left = right;
  21.                 right = left+1;
  22.                 curInterVal = intervals.get(left);
  23.             }
  24.         }
  25.         ans.add(curInterVal);
  26.         return ans;
  27.     }
  29.     private boolean canMerge(Interval inte1,Interval inte2){
  30.         //[start1,end1] [start2,end2], start1<start2
  31.         if(inte2.start<=inte1.end){
  32.             return true;
  33.         }
  34.         return false;
  35.     }
  36.     private Interval mergeInterval(Interval inte1,Interval inte2){
  37.         return new Interval(inte1.start,Math.max(inte1.end,inte2.end));
  38.     }
  39. }