foo.cc: In function 'int shu(char*)':
foo.cc:24:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
foo.cc: In function 'int main()':
foo.cc:9:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    scanf("%[^\n]%[^\n]",s1,s2);
    ~~~~~^~~~~~~~~~~~~~~~~~~~~~
foo.cc: In function 'int shu(char*)':
foo.cc:18:10: warning: 'i' is used uninitialized in this function [-Wuninitialized]
  for(;s[i]!=0 ;i++)
          ^

自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。