foo.cpp: In function 'void init()':
foo.cpp:59:30: error: 'qsort' was not declared in this scope
  qsort(p+1,n,sizeof(p[1]),cmp);
                              ^
foo.cpp: In function 'void work()':
foo.cpp:67:41: error: 'memcpy' was not declared in this scope
     if (ncmp()>0) memcpy(ans,b,sizeof(b)); 
                                         ^