/in/foo.cc: In function 'int main()':
/in/foo.cc:42:12: warning: 'p' may be used uninitialized in this function [-Wmaybe-uninitialized]
         o[p]++; 
         ~~~^
/in/foo.cc:30:12: warning: 'p' may be used uninitialized in this function [-Wmaybe-uninitialized]
         c[p]++;//桶排不解释 
         ~~~^