LeetCode 56. 合并区间

 1 vector<vector<int>> merge(vector<vector<int>>& intervals) {
 2         sort(intervals.begin(),intervals.end()); // sort是什么机制?为什么能够对vector<vector<int>>直接sort，好强;
 3         if(intervals.size()<=1){
 4             return intervals;
 5         }
 6         auto p1=intervals.begin();
 7         auto p2=intervals.begin()+1;
 8         while(p2!=intervals.end()){
 9             // 考虑p2[0]和p1[1]的关系
10             if((*p2)[0]<=(*p1)[1]){
11                 int tmp=max((*p2)[1],(*p1)[1]);
12                 (*p1)[1]=tmp;
13             }
14             else{
15                 p1++;
16                 p1->swap(*p2);
17             }
18             p2++;
19         }
20         intervals.erase(++p1,intervals.end());
21         return intervals;
22     }