合并区间

 塞入map后，【1,4】被合并了，只剩下一个了。导致后续跳过了

 

 

class Solution {
public:
// 失败 1 思路错 不应该和上一个比较 而是和上一次合并的结果比较
    vector<vector<int>> merge1(vector<vector<int>>& intervals) {

        // 1 排序
        map<int,vector<int>> map_list;

        vector<vector<int>> result;
        if (intervals.empty()) {
            return result;
            }

        if(intervals.size()==1){
             return intervals;
        }

        for(int i=0;i<intervals.size();i++){
            map_list[intervals[i][0]]=intervals[i]; 
        }
        
       for (auto it = map_list.begin(); it != map_list.end(); ++it) {
           


           int last_begin=it->second[0];
           int last_end=it->second[it->second.size()-1];
           auto next_it = std::next(it);

           if(next_it==map_list.end()){

              result.push_back(it->second);  
              break;
           }

           int current_begin=next_it->second[0];
           int current_end=next_it->second[next_it->second.size()-1];
          
        //    cout<<" last_end "<< last_end
        //    <<" current_begin "<< current_begin
        //    <<endl;
           if(last_end>=current_begin){
               
               vector<int> temp_;
               temp_.push_back(last_begin);
               temp_.push_back(max(last_end,current_end));
           
               result.push_back(temp_);

               it=std::next(it);

           }
           else{

              result.push_back(it->second);
           }
           
           
        }
       


        return result;
    }
// 自己成功1 14% 用时  8.9 内存 map 耗费时间和空间
     vector<vector<int>> merge_map(vector<vector<int>>& intervals) {

        // 1 排序
        map<int,vector<int>> map_list;

        vector<vector<int>> result;

        for(int i=0;i<intervals.size();i++){
            if(map_list.contains(intervals[i][0])){
                int old_max = map_list[intervals[i][0]][1];
                int now_max = intervals[i][1];
                map_list[intervals[i][0]]={intervals[i][0],max(old_max,now_max)}; 
            }
            else{
                map_list[intervals[i][0]]=intervals[i]; 
            }
        }
        
       result.push_back(map_list.begin()->second);


       for (auto it = std::next(map_list.begin()); it != map_list.end(); ++it) {
           
           vector<int> last_v=result.back();

           int last_begin=last_v[0];
           int last_end=last_v[1];
         
           int current_begin=it->second[0];
           int current_end=it->second[1];

        //    cout
        //    << " last_begin "<< last_begin
        //    << " |last_end " <<  last_end
        //    << " |current_begin "<<current_begin 
        //    << " |current_end " <<  current_end
        //    <<endl;

           if(last_end>=current_begin){

               result.pop_back(); 
                
               last_v={last_begin,max(last_end,current_end)};
               
               result.push_back(last_v);

           }
           else{
              
              result.push_back(it->second);
              last_v=it->second;
           }
           
           
        }
       


        return result;
    }


        vector<vector<int>> merge(vector<vector<int>>& intervals) {

        // 1 排序
        map<int,vector<int>> map_list;

        vector<vector<int>> result;

        for(int i=0;i<intervals.size();i++){
            if(map_list.contains(intervals[i][0])){
                int old_max = map_list[intervals[i][0]][1];
                int now_max = intervals[i][1];
                map_list[intervals[i][0]]={intervals[i][0],max(old_max,now_max)}; 
            }
            else{
                map_list[intervals[i][0]]=intervals[i]; 
            }
        }
        
       result.push_back(map_list.begin()->second);


       for (auto it = std::next(map_list.begin()); it != map_list.end(); ++it) {
           
           vector<int> last_v=result.back();

           int last_begin=last_v[0];
           int last_end=last_v[1];
         
           int current_begin=it->second[0];
           int current_end=it->second[1];

        //    cout
        //    << " last_begin "<< last_begin
        //    << " |last_end " <<  last_end
        //    << " |current_begin "<<current_begin 
        //    << " |current_end " <<  current_end
        //    <<endl;

           if(last_end>=current_begin){

               result.pop_back(); 
                
               last_v={last_begin,max(last_end,current_end)};
               
               result.push_back(last_v);

           }
           else{
              
              result.push_back(it->second);
              last_v=it->second;
           }
           
           
        }
       


        return result;
    }
};