使用STL中的map时候，有时候需要使用结构题自定义键值，比如想统计点的坐标出现的次数

struct Node{    int x,y;};......map
     
      mp;mp[(Node){x,y}]++;
     

　　这样子的话，会出现一堆报错

c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h||In instantiation of 'bool std::less<_Tp>::operator()(const _Tp&, const _Tp&) const [with _Tp = Node]':|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_map.h|483|required from 'std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](std::map<_Key, _Tp, _Compare, _Alloc>::key_type&&) [with _Key = Node; _Tp = int; _Compare = std::less
     
      ; _Alloc = std::allocator
      
       
         >; std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type = int; std::map<_Key, _Tp, _Compare, _Alloc>::key_type = Node]'|E:\Programming Design\practice\ceshi.cpp|27|required from here|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|error: no match for 'operator<' (operand types are 'const Node' and 'const Node')|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: candidates are:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_pair.h|220|note: template
        
          constexpr bool std::operator<(const std::pair<_T1, _T2>&, const std::pair<_T1, _T2>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_pair.h|220|note:   template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note:   'const Node' is not derived from 'const std::pair<_T1, _T2>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_iterator.h|297|note: template
         
           bool std::operator<(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_Iterator>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_iterator.h|297|note:   template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note:   'const Node' is not derived from 'const std::reverse_iterator<_Iterator>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_iterator.h|347|note: template
          
            bool std::operator<(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_IteratorR>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_iterator.h|347|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::reverse_iterator<_Iterator>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_iterator.h|1055|note: template
           
             bool std::operator<(const std::move_iterator<_Iterator>&, const std::move_iterator<_IteratorR>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_iterator.h|1055|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::move_iterator<_Iterator>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_iterator.h|1061|note: template
            
              bool std::operator<(const std::move_iterator<_Iterator>&, const std::move_iterator<_Iterator>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_iterator.h|1061|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::move_iterator<_Iterator>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\basic_string.h|2569|note: template
             
               bool std::operator<(const std::basic_string<_CharT, _Traits, _Alloc>&, const std::basic_string<_CharT, _Traits, _Alloc>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\basic_string.h|2569|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::basic_string<_CharT, _Traits, _Alloc>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\basic_string.h|2581|note: template
              
                bool std::operator<(const std::basic_string<_CharT, _Traits, _Alloc>&, const _CharT*)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\basic_string.h|2581|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::basic_string<_CharT, _Traits, _Alloc>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\basic_string.h|2593|note: template
               
                 bool std::operator<(const _CharT*, const std::basic_string<_CharT, _Traits, _Alloc>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\basic_string.h|2593|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: mismatched types 'const _CharT*' and 'Node'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_vector.h|1420|note: template
                
                  bool std::operator<(const std::vector<_Tp, _Alloc>&, const std::vector<_Tp, _Alloc>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_vector.h|1420|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::vector<_Tp, _Alloc>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\array|238|note: template
                 
                   bool std::operator<(const std::array<_Tp, _Nm>&, const std::array<_Tp, _Nm>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\array|238|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::array<_Tp, _Nm>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\tuple|822|note: template
                  
                    constexpr bool std::operator<(const std::tuple<_Elements ...>&, const std::tuple<_Elements ...>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\tuple|822|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::tuple<_Elements ...>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_deque.h|273|note: template
                   
                     bool std::operator<(const std::_Deque_iterator<_Tp, _Ref, _Ptr>&, const std::_Deque_iterator<_Tp, _Ref, _Ptr>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_deque.h|273|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::_Deque_iterator<_Tp, _Ref, _Ptr>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_deque.h|281|note: template
                    
                      bool std::operator<(const std::_Deque_iterator<_Tp, _Ref, _Ptr>&, const std::_Deque_iterator<_Tp, _RefR, _PtrR>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_deque.h|281|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::_Deque_iterator<_Tp, _Ref, _Ptr>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_deque.h|1975|note: template
                     
                       bool std::operator<(const std::deque<_Tp, _Alloc>&, const std::deque<_Tp, _Alloc>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_deque.h|1975|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::deque<_Tp, _Alloc>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_list.h|1631|note: template
                      
                        bool std::operator<(const std::list<_Tp, _Alloc>&, const std::list<_Tp, _Alloc>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_list.h|1631|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::list<_Tp, _Alloc>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_tree.h|914|note: template
                       
                         bool std::operator<(const std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>&, const std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_tree.h|914|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_map.h|978|note: template
                        
                          bool std::operator<(const std::map<_Key, _Tp, _Compare, _Alloc>&, const std::map<_Key, _Tp, _Compare, _Alloc>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_map.h|978|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::map<_Key, _Tp, _Compare, _Alloc>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_multimap.h|880|note: template
                         
                           bool std::operator<(const std::multimap<_Key, _Tp, _Compare, _Alloc>&, const std::multimap<_Key, _Tp, _Compare, _Alloc>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_multimap.h|880|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::multimap<_Key, _Tp, _Compare, _Alloc>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\unique_ptr.h|523|note: template
                          
                            bool std::operator<(const std::unique_ptr<_Tp, _Dp>&, const std::unique_ptr<_Up, _Ep>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\unique_ptr.h|523|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::unique_ptr<_Tp, _Dp>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\unique_ptr.h|534|note: template
                           
                             bool std::operator<(const std::unique_ptr<_Tp, _Dp>&, std::nullptr_t)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\unique_ptr.h|534|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::unique_ptr<_Tp, _Dp>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\unique_ptr.h|540|note: template
                            
                              bool std::operator<(std::nullptr_t, const std::unique_ptr<_Tp, _Dp>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\unique_ptr.h|540|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: cannot convert '__x' (type 'const Node') to type 'std::nullptr_t'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\shared_ptr_base.h|1090|note: template
                             
                               bool std::operator<(const std::__shared_ptr<_Tp1, _Lp>&, const std::__shared_ptr<_Tp2, _Lp>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\shared_ptr_base.h|1090|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::__shared_ptr<_Tp1, _Lp>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\shared_ptr_base.h|1099|note: template
                              
                                bool std::operator<(const std::__shared_ptr<_Tp, _Lp>&, std::nullptr_t)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\shared_ptr_base.h|1099|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::__shared_ptr<_Tp, _Lp>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\shared_ptr_base.h|1104|note: template
                               
                                 bool std::operator<(std::nullptr_t, const std::__shared_ptr<_Tp, _Lp>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\shared_ptr_base.h|1104|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: cannot convert '__x' (type 'const Node') to type 'std::nullptr_t'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\shared_ptr.h|359|note: template
                                
                                  bool std::operator<(const std::shared_ptr<_Tp1>&, const std::shared_ptr<_Tp2>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\shared_ptr.h|359|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::shared_ptr<_Tp1>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\shared_ptr.h|368|note: template
                                 
                                   bool std::operator<(const std::shared_ptr<_Tp1>&, std::nullptr_t)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\shared_ptr.h|368|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::shared_ptr<_Tp1>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\shared_ptr.h|373|note: template
                                  
                                    bool std::operator<(std::nullptr_t, const std::shared_ptr<_Tp1>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\shared_ptr.h|373|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: cannot convert '__x' (type 'const Node') to type 'std::nullptr_t'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_queue.h|286|note: template
                                   
                                     bool std::operator<(const std::queue<_Tp, _Seq>&, const std::queue<_Tp, _Seq>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_queue.h|286|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::queue<_Tp, _Seq>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_set.h|769|note: template
                                    
                                      bool std::operator<(const std::set<_Key, _Compare, _Alloc>&, const std::set<_Key, _Compare, _Alloc>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_set.h|769|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::set<_Key, _Compare, _Alloc>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_multiset.h|754|note: template
                                     
                                       bool std::operator<(const std::multiset<_Key, _Compare, _Alloc>&, const std::multiset<_Key, _Compare, _Alloc>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_multiset.h|754|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::multiset<_Key, _Compare, _Alloc>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_stack.h|261|note: template
                                      
                                        bool std::operator<(const std::stack<_Tp, _Seq>&, const std::stack<_Tp, _Seq>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_stack.h|261|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::stack<_Tp, _Seq>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\valarray_after.h|416|note: template
                                       
                                         std::_Expr
                                        
                                         
                                          , typename std::__fun
                                          
                                           ::result_type> std::operator<(const std::_Expr<_Dom1, typename _Dom1::value_type>&, const std::_Expr<_Dom2, typename _Dom2::value_type>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\valarray_after.h|416|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\valarray_after.h|416|note: template
                                           
                                             std::_Expr
                                            
                                             
                                              , typename std::__fun
                                              
                                               ::result_type> std::operator<(const std::_Expr<_Dom1, typename _Dom1::value_type>&, const typename _Dom::value_type&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\valarray_after.h|416|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\valarray_after.h|416|note: template
                                               
                                                 std::_Expr
                                                
                                                 
                                                  , typename std::__fun
                                                  
                                                   ::result_type> std::operator<(const typename _Dom::value_type&, const std::_Expr<_Dom1, typename _Dom1::value_type>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\valarray_after.h|416|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\valarray_after.h|416|note: template
                                                   
                                                     std::_Expr
                                                    
                                                     
                                                      , typename std::__fun
                                                      
                                                       ::result_type> std::operator<(const std::_Expr<_Dom1, typename _Dom1::value_type>&, const std::valarray
                                                       
                                                        &)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\valarray_after.h|416|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\valarray_after.h|416|note: template
                                                        
                                                          std::_Expr
                                                         
                                                          
                                                           , typename std::__fun
                                                           
                                                            ::result_type> std::operator<(const std::valarray
                                                            
                                                             &, const std::_Expr<_Dom1, typename _Dom1::value_type>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\valarray_after.h|416|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::valarray
                                                             
                                                              '|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\valarray|1168|note: template
                                                              
                                                                std::_Expr
                                                               
                                                                
                                                                 , typename std::__fun
                                                                 
                                                                  ::result_type> std::operator<(const std::valarray<_Tp>&, const std::valarray<_Tp>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\valarray|1168|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::valarray<_Tp>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\valarray|1168|note: template
                                                                  
                                                                    std::_Expr
                                                                   
                                                                    
                                                                     , typename std::__fun
                                                                     
                                                                      ::result_type> std::operator<(const std::valarray<_Tp>&, const _Tp&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\valarray|1168|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::valarray<_Tp>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\valarray|1168|note: template
                                                                      
                                                                        std::_Expr
                                                                       
                                                                        
                                                                         , typename std::__fun
                                                                         
                                                                          ::result_type> std::operator<(const _Tp&, const std::valarray<_Tp>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\valarray|1168|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::valarray<_Tp>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\system_error|177|note: bool std::operator<(const std::error_code&, const std::error_code&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\system_error|177|note: no known conversion for argument 1 from 'const Node' to 'const std::error_code&'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\system_error|250|note: bool std::operator<(const std::error_condition&, const std::error_condition&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\system_error|250|note: no known conversion for argument 1 from 'const Node' to 'const std::error_condition&'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\forward_list.h|1359|note: template
                                                                          
                                                                            bool std::operator<(const std::forward_list<_Tp, _Alloc>&, const std::forward_list<_Tp, _Alloc>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\forward_list.h|1359|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::forward_list<_Tp, _Alloc>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\regex.h|879|note: template
                                                                           
                                                                             bool std::operator<(const std::sub_match<_BiIter>&, const std::sub_match<_BiIter>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\regex.h|879|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::sub_match<_BiIter>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\regex.h|955|note: template
                                                                            
                                                                              bool std::operator<(std::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&, const std::sub_match<_BiIter>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\regex.h|955|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'std::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\regex.h|1029|note: template
                                                                             
                                                                               bool std::operator<(const std::sub_match<_BiIter>&, std::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\regex.h|1029|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::sub_match<_BiIter>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\regex.h|1103|note: template
                                                                              
                                                                                bool std::operator<(const typename std::iterator_traits<_Iter>::value_type*, const std::sub_match<_BiIter>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\regex.h|1103|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: mismatched types 'const typename std::iterator_traits<_Iter>::value_type*' and 'Node'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\regex.h|1177|note: template
                                                                               
                                                                                 bool std::operator<(const std::sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\regex.h|1177|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::sub_match<_BiIter>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\regex.h|1254|note: template
                                                                                
                                                                                  bool std::operator<(const typename std::iterator_traits<_Iter>::value_type&, const std::sub_match<_BiIter>&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\regex.h|1254|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::sub_match<_BiIter>'|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\regex.h|1334|note: template
                                                                                 
                                                                                   bool std::operator<(const std::sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\regex.h|1334|note: template argument deduction/substitution failed:|c:\mingw\lib\gcc\mingw32\4.8.1\include\c++\bits\stl_function.h|235|note: 'const Node' is not derived from 'const std::sub_match<_BiIter>'|||=== Build failed: 1 error(s), 3 warning(s) (0 minute(s), 4 second(s)) ===|
                                                                                 
                                                                                
                                                                               
                                                                              
                                                                             
                                                                            
                                                                           
                                                                          
                                                                         
                                                                        
                                                                       
                                                                      
                                                                     
                                                                    
                                                                   
                                                                  
                                                                 
                                                                
                                                               
                                                              
                                                             
                                                            
                                                           
                                                          
                                                         
                                                        
                                                       
                                                      
                                                     
                                                    
                                                   
                                                  
                                                 
                                                
                                               
                                              
                                             
                                            
                                           
                                          
                                         
                                        
                                       
                                      
                                     
                                    
                                   
                                  
                                 
                                
                               
                              
                             
                            
                           
                          
                         
                        
                       
                      
                     
                    
                   
                  
                 
                
               
              
             
            
           
          
         
        
       
      
     

　　看着似乎满屏错误，其实就是少了一个键值比较函数，因为我们知道map插入键值后默认从小到大排序，使用自定义结构体作为键值，但是没有自定义比较函数的话，编译器无法为插入的元素排序。

struct Node{    int x,y;    bool operator < (const Node &a)const    {        if (x == a.x)   return y < a.y;        else return x < a.x;    }};

　　这样子修改后，就可以成功运行了。其实从这个例子，我们可以类比用结构体自定义优先队列，也是需要自写比较函数的。