View Compilation Error

0_0_39621282_28032.cpp: In function 'void slove()':
0_0_39621282_28032.cpp:72:2: error: invalid operands of types 'std::string [n]' {aka 'std::__cxx11::basic_string<char> [n]'} and 'std::string*' {aka 'std::__cxx11::basic_string<char>*'} to binary 'operator+'
   72 | s+=s;
      | ~^~~
0_0_39621282_28032.cpp:72:2: note:   in evaluation of 'operator+=(std::string [n] {aka class std::__cxx11::basic_string<char> [n]}, std::string* {aka class std::__cxx11::basic_string<char>*})'