interval intersection

class Interval{
  int start;
  int end;
}


public List<Integer> intersection(List<Interval> l1, List<Interval> l2){
  List<Interval> res = new ArrayList<>();
  int i = 0;
  int j = 0;
  while(i < l1.length && j < l2.length){
    if(l1[i].end <= l2[j].end){
      if(l1[i].end > l2[j].start){
        res.add(new Interval(Math.max(l1[i].start, l2[j].start), l1[i].end));
      }
      i++;
    }else{
      if(l2[j].end > l1[i].start){
        res.add(new Interval(Math.max(l1[i].start, l2[j].start), l2[j].end));
      }
      j++;
    }
  }
  return res;
}

 example： input is two non-overlapping list of intervals , output is the list of overlaps 

 

l1 : [0, 2], [5, 7]. [9, 11]

l2: [1, 3], [6, 10]

 

overlap is [1, 2]. [6, 7], [9, 10]