/in/foo.cc: In function 'void check(std::__cxx11::string&)':
/in/foo.cc:42:5: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
  if ( b > 0) //如果左括号多了
     ^
/in/foo.cc: In function 'int reduce(std::__cxx11::string)':
/in/foo.cc:194:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'int find(std::__cxx11::string)':
/in/foo.cc:130:9: warning: 'k' may be used uninitialized in this function [-Wmaybe-uninitialized]
  return k;
         ^