acwing56. 合并区间

class Solution {
public:
    
    vector<vector<int>> merge(vector<vector<int>>& intervals) {
            vector<vector<int>> merged;
            sort(intervals.begin(),intervals.end());
            for(int i=0;i<intervals.size();i++){
                int l=intervals[i][0],r=intervals[i][1];
                if(!merged.size()||merged.back()[1]<l){
                    merged.push_back({l,r});
                }else{
                    merged.back()[1]=max( merged.back()[1],r);
                }
            }
            return merged;
    }
};