foo.c: In function 'main':
foo.c:38:5: error: 't' undeclared (first use in this function)
  if(t->top==-1)
     ^
foo.c:38:5: note: each undeclared identifier is reported only once for each function it appears in
foo.c:19:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%s",sentences);
  ^

自豪的采用 HydroJudger 进行评测(github.com/hydro-dev/HydroJudger)