foo.cc: In function 'int bfs(int, int)':
foo.cc:41:1: warning: no return statement in function returning non-void [-Wreturn-type]
 }
 ^
foo.cc: In function 'int main()':
foo.cc:68:25: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
   if(a[p[i].x][p[i].y]=1) a[p[i].x][p[i].y]=0;
                         ^
foo.cc:58:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&n,&m);
                     ^
foo.cc:62:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&a[i][j]);
                       ^
foo.cc:64:16: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&t);
                ^
foo.cc:67:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",&p[i].x,&p[i].y);
                                ^

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

{"receive":"2020-05-13T08:13:10.510Z","handle":"2020-05-13T08:13:10.510Z","cache_start":"2020-05-13T08:13:10.520Z","read_cases":"2020-05-13T08:13:10.668Z","judge":"2020-05-13T08:13:10.670Z","done":"2020-05-13T08:13:14.354Z"}