foo.cc: In function 'void debug(T, int, int)':
foo.cc:30:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  for (int i=l;i<=r;i++) write(a[i]),putchar(' '); writeln();
  ^~~
foo.cc:30:51: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
  for (int i=l;i<=r;i++) write(a[i]),putchar(' '); writeln();
                                                   ^~~~~~~
foo.cc: In member function 'int FHQ_treap::merge(int, int)':
foo.cc:56:3: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   if (!x||!y) return x|y; int ret;
   ^~
foo.cc:56:27: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   if (!x||!y) return x|y; int ret;
                           ^~~
foo.cc: In function 'int main()':
foo.cc:160:2: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
  for (int i=1;i<=n;i++) scanf("%d",a+i); st.build(1,1,n); //st.print(1,1,n);
  ^~~
foo.cc:160:42: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
  for (int i=1;i<=n;i++) scanf("%d",a+i); st.build(1,1,n); //st.print(1,1,n);
                                          ^~
foo.cc:159:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&n,&m);
  ~~~~~^~~~~~~~~~~~~~
foo.cc:160:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for (int i=1;i<=n;i++) scanf("%d",a+i); st.build(1,1,n); //st.print(1,1,n);
                         ~~~~~^~~~~~~~~~
foo.cc:163:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   char opt[5]; scanf("%s",opt);
                ~~~~~^~~~~~~~~~
foo.cc:166:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     int l,r,x; scanf("%d%d%d",&l,&r,&x); writeln(st.query_kth(l,r,x)); break;
                ~~~~~^~~~~~~~~~~~~~~~~~~
foo.cc:169:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     int pos,x; scanf("%d%d",&pos,&x); st.update(1,1,n,pos,a[pos],x); a[pos] = x; break;
                ~~~~~^~~~~~~~~~~~~~~~

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

{"receive":"2020-05-24T04:01:05.446Z","handle":"2020-05-24T04:01:05.446Z","cache_start":"2020-05-24T04:01:05.453Z","read_cases":"2020-05-24T04:01:07.403Z","judge":"2020-05-24T04:01:07.403Z","done":"2020-05-24T04:01:13.025Z"}