/in/foo.c: In function 'emptynode':
/in/foo.c:15:10: warning: assignment makes integer from pointer without a cast [-Wint-conversion]
  p->data = NULL;
          ^
/in/foo.c: In function 'solve':
/in/foo.c:68:2: warning: 'q' may be used uninitialized in this function [-Wmaybe-uninitialized]
  printf("%d ",q->data );
  ^~~~~~~~~~~~~~~~~~~~~~