Merge Intervals

class Solution {
public:
    vector<vector<int>> merge(vector<vector<int>>& intervals) {
        vector<vector<int>> res;        
        sort(intervals.begin(),intervals.end());
        int st=-2e4,ed=-2e4;
        for(auto item:intervals) {
            if(ed<item[0]) {
                if(st!=-2e4) res.push_back({st,ed});
                st=item[0],ed=item[1];
            }
            else ed=max(ed,item[1]);
        }
        if(st!=-2e4) res.push_back({st,ed});
        return res;
    }
};