Submission #444525

#	Time	Username	Problem	Language	Result	Execution time	Memory
444525		minhcool	Examination (JOI19_examination)	C++17	Compilation error	0 ms	0 KiB

examination

examination
#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;
 
#define hash hashy
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define foru(i, l, r) for(int i = l; i <= r; i++)
#define ford(i, r, l) for(int i = r; i >= l; i--)
 
typedef pair<int, int> ii;
typedef pair<ii, int> iii;
typedef pair<ii, ii> iiii;
 
const int N = 2e5 + 5, block = 900;
 
const int oo = 1e18 + 7, mod = 1e9 + 7;
 
int n, q;
 
unordered_map<int, int> uomp;
vector<int> vc;
 
iii queries[N];
ii students1[N], students2[N];
 
vector<int> srt[N/block];
 
int bit[N];
bool in[N];
 
int answer[N];
int counter = 0;
 
void upd(int pos, int val){
	counter++;
	for(; pos <= n + q; pos += pos & -pos) bit[pos] += val;
}
 
int get(int pos){
	int ans = 0;
	for(; pos; pos -= pos & -pos) ans += bit[pos];
	return ans;
}
 
bool cmp(int a, int b){
	return (queries[a].fi.fi > queries[b].fi.fi);
}
 
ii que[N];
 
void process(){
	cin >> n >> q;
	vector<int> vc;
	for(int i = 1; i <= n; i++){
		cin >> students1[i].fi >> students1[i].se;
		vc.pb(students1[i].se);
		students2[i] = {students1[i].fi + students1[i].se, i};
	}
	//if(n == 100000 && q == 100000 && students1[i].fi == 92665) return;
	sort(students2 + 1, students2 + n + 1);
	for(int i = 1; i <= q; i++){
		cin >> queries[i].fi.fi >> queries[i].fi.se >> queries[i].se;
		vc.pb(queries[i].fi.se);
		int pos = lower_bound(students2 + 1, students2 + n + 1, make_pair(queries[i].se, 0)) - students2;
		srt[pos / block].pb(i);
	}
	sort(vc.begin(), vc.end());
	vc.resize(unique(vc.begin(), vc.end()) - vc.begin());
	for(int i = 0; i < vc.size(); i++) uomp[vc[i]] = i + 1;
	set<ii> se;
	for(int i = n/block + 2; i >= 0; i--){// l = (i * block), r = (i + 1) * block - 1
		//cout << i << "\n";
		int itr = 0;
		for(set<ii>::iterator it = se.begin(); it != se.end(); it++){
			itr++;
			que[itr] = (*it);
		}
		//stack<ii> que;
		//for(set<ii>::iterator it = se.begin(); it != se.end(); it++) que.push(it);
		sort(srt[i].begin(), srt[i].end(), cmp);
		for(int j = 1; j <= n + q; j++) bit[j] = 0;
		for(int j = 1; j <= n; j++) in[j] = 0; 
		int lst = min(n + 1, (i + 1) * block);
		vector<ii> vc1;
		for(int j = max(1, i * block); j < min(n + 1, (i + 1) * block); j++){
			int tmp = students2[j].se;
			//if(!tmp) cout << j << " " << tmp << "\n";
			vc1.pb({students1[tmp].fi, tmp});
		}
		sort(vc1.begin(), vc1.end());
		for(auto it : srt[i]){
			//cout << it << " " << i << "\n";
				while(1){
					if(!itr) break;
					ii temp = que[itr];
					//int x = que.top().fi;
					if(temp.fi < queries[it].fi.fi) break;
					//cout << x << " " << que.size() << "\n";
					in[temp.se] = 1;
					upd(uomp[students1[temp.se].se], 1);
					itr--;
				}
			int temp = lower_bound(students2 + 1, students2 + n + 1, make_pair(queries[it].se, 0)) - students2;
			//cout << it << " " << temp << "\n";
			//cout << lst << " " << temp << " " << queries[it].se << "\n";
			//continue;
			for(int j = lst; j < temp; j++){
				if(in[students2[j].se]){
					in[students2[j].se] = 0;
					upd(uomp[students1[students2[j].se].se], -1);
				}
			} 
			for(int j = temp; j < lst; j++){
				if(students1[students2[j].se].fi >= queries[it].fi.fi && !in[students2[j].se]){
					in[students2[j].se] = 1;
					upd(uomp[students1[students2[j].se].se], 1);
				}
			}
			lst = temp;
			while(1){
				if(!vc1.size()) break;
				if(vc1.back().fi < queries[it].fi.fi) break;
				int ind = vc1.back().se;
				if(!in[ind] && students1[ind].fi + students1[ind].se >= queries[it].se){
					in[ind] = 1;
					//assert(ind);
					upd(uomp[students1[ind].se], 1);
				}
				vc1.pop_back();
				//cout << vc1.size() << "\n";
			}
			answer[it] = get(n + q) - get(uomp[queries[it].fi.se] - 1);
	        //if(double)clock() / CLOCKS_PER_SEC;
		}
		for(int j = i * block; j < min(n + 1, (i + 1) * block); j++){
			int tmp = students2[j].se;
			//cout << j << " " << tmp << "\n";
			se.insert({students1[tmp].fi, tmp});
		}
	}
	//cout << counter << "\n";
	//cout << (double)clock() / CLOCKS_PER_SEC;
	for(int i = 1; i <= q; i++) cout << answer[i] << "\n";
}
 
signed main(){
	ios_base::sync_with_stdio(0);
	//freopen("exam.txt", "r", stdin);
	process();
    return 101;
}

Compilation message (stderr)

examination.cpp:1:1: error: 'examination' does not name a type
    1 | examination
      | ^~~~~~~~~~~
In file included from /usr/include/c++/10/cmath:43,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from examination.cpp:2:
/usr/include/c++/10/ext/type_traits.h:162:35: error: 'bool __gnu_cxx::__is_null_pointer' redeclared as different kind of entity
  162 |   __is_null_pointer(std::nullptr_t)
      |                                   ^
/usr/include/c++/10/ext/type_traits.h:157:5: note: previous declaration 'template<class _Type> bool __gnu_cxx::__is_null_pointer(_Type)'
  157 |     __is_null_pointer(_Type)
      |     ^~~~~~~~~~~~~~~~~
/usr/include/c++/10/ext/type_traits.h:162:26: error: 'nullptr_t' is not a member of 'std'
  162 |   __is_null_pointer(std::nullptr_t)
      |                          ^~~~~~~~~
In file included from /usr/include/c++/10/bits/move.h:57,
                 from /usr/include/c++/10/bits/stl_pair.h:59,
                 from /usr/include/c++/10/bits/stl_algobase.h:64,
                 from /usr/include/c++/10/bits/specfun.h:45,
                 from /usr/include/c++/10/cmath:1927,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from examination.cpp:2:
/usr/include/c++/10/type_traits:402:26: error: 'std::size_t' has not been declared
  402 |   template<typename _Tp, std::size_t _Size>
      |                          ^~~
/usr/include/c++/10/type_traits:403:25: error: '_Size' was not declared in this scope
  403 |     struct is_array<_Tp[_Size]>
      |                         ^~~~~
/usr/include/c++/10/type_traits:403:31: error: template argument 1 is invalid
  403 |     struct is_array<_Tp[_Size]>
      |                               ^
/usr/include/c++/10/type_traits:508:42: error: 'nullptr_t' is not a member of 'std'
  508 |     struct __is_null_pointer_helper<std::nullptr_t>
      |                                          ^~~~~~~~~
/usr/include/c++/10/type_traits:508:51: error: template argument 1 is invalid
  508 |     struct __is_null_pointer_helper<std::nullptr_t>
      |                                                   ^
/usr/include/c++/10/type_traits:1351:37: error: 'size_t' is not a member of 'std'; did you mean 'size_t'?
 1351 |     : public integral_constant<std::size_t, alignof(_Tp)>
      |                                     ^~~~~~
In file included from /usr/include/stdlib.h:31,
                 from /usr/include/c++/10/bits/std_abs.h:38,
                 from /usr/include/c++/10/cmath:47,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from examination.cpp:2:
/usr/lib/gcc/x86_64-linux-gnu/10/include/stddef.h:209:23: note: 'size_t' declared here
  209 | typedef __SIZE_TYPE__ size_t;
      |                       ^~~~~~
In file included from /usr/include/c++/10/bits/move.h:57,
                 from /usr/include/c++/10/bits/stl_pair.h:59,
                 from /usr/include/c++/10/bits/stl_algobase.h:64,
                 from /usr/include/c++/10/bits/specfun.h:45,
                 from /usr/include/c++/10/cmath:1927,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from examination.cpp:2:
/usr/include/c++/10/type_traits:1351:57: error: template argument 1 is invalid
 1351 |     : public integral_constant<std::size_t, alignof(_Tp)>
      |                                                         ^
/usr/include/c++/10/type_traits:1351:57: note: invalid template non-type parameter
/usr/include/c++/10/type_traits:1360:37: error: 'size_t' is not a member of 'std'; did you mean 'size_t'?
 1360 |     : public integral_constant<std::size_t, 0> { };
      |                                     ^~~~~~
In file included from /usr/include/stdlib.h:31,
                 from /usr/include/c++/10/bits/std_abs.h:38,
                 from /usr/include/c++/10/cmath:47,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from examination.cpp:2:
/usr/lib/gcc/x86_64-linux-gnu/10/include/stddef.h:209:23: note: 'size_t' declared here
  209 | typedef __SIZE_TYPE__ size_t;
      |                       ^~~~~~
In file included from /usr/include/c++/10/bits/move.h:57,
                 from /usr/include/c++/10/bits/stl_pair.h:59,
                 from /usr/include/c++/10/bits/stl_algobase.h:64,
                 from /usr/include/c++/10/bits/specfun.h:45,
                 from /usr/include/c++/10/cmath:1927,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from examination.cpp:2:
/usr/include/c++/10/type_traits:1360:46: error: template argument 1 is invalid
 1360 |     : public integral_constant<std::size_t, 0> { };
      |                                              ^
/usr/include/c++/10/type_traits:1360:46: note: invalid template non-type parameter
/usr/include/c++/10/type_traits:1362:26: error: 'std::size_t' has not been declared
 1362 |   template<typename _Tp, std::size_t _Size>
      |                          ^~~
/usr/include/c++/10/type_traits:1363:21: error: '_Size' was not declared in this scope
 1363 |     struct rank<_Tp[_Size]>
      |                     ^~~~~
/usr/include/c++/10/type_traits:1363:27: error: template argument 1 is invalid
 1363 |     struct rank<_Tp[_Size]>
      |                           ^
/usr/include/c++/10/type_traits:1364:37: error: 'size_t' is not a member of 'std'; did you mean 'size_t'?
 1364 |     : public integral_constant<std::size_t, 1 + rank<_Tp>::value> { };
      |                                     ^~~~~~
In file included from /usr/include/stdlib.h:31,
                 from /usr/include/c++/10/bits/std_abs.h:38,
                 from /usr/include/c++/10/cmath:47,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from examination.cpp:2:
/usr/lib/gcc/x86_64-linux-gnu/10/include/stddef.h:209:23: note: 'size_t' declared here
  209 | typedef __SIZE_TYPE__ size_t;
      |                       ^~~~~~
In file included from /usr/include/c++/10/bits/move.h:57,
                 from /usr/include/c++/10/bits/stl_pair.h:59,
                 from /usr/include/c++/10/bits/stl_algobase.h:64,
                 from /usr/include/c++/10/bits/specfun.h:45,
                 from /usr/include/c++/10/cmath:1927,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from examination.cpp:2:
/usr/include/c++/10/type_traits:1364:65: error: template argument 1 is invalid
 1364 |     : public integral_constant<std::size_t, 1 + rank<_Tp>::value> { };
      |                                                                 ^
/usr/include/c++/10/type_traits:1364:65: note: invalid template non-type parameter
/usr/include/c++/10/type_traits:1368:37: error: 'size_t' is not a member of 'std'; did you mean 'size_t'?
 1368 |     : public integral_constant<std::size_t, 1 + rank<_Tp>::value> { };
      |                                     ^~~~~~
In file included from /usr/include/stdlib.h:31,
                 from /usr/include/c++/10/bits/std_abs.h:38,
                 from /usr/include/c++/10/cmath:47,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from examination.cpp:2:
/usr/lib/gcc/x86_64-linux-gnu/10/include/stddef.h:209:23: note: 'size_t' declared here
  209 | typedef __SIZE_TYPE__ size_t;
      |                       ^~~~~~
In file included from /usr/include/c++/10/bits/move.h:57,
                 from /usr/include/c++/10/bits/stl_pair.h:59,
                 from /usr/include/c++/10/bits/stl_algobase.h:64,
                 from /usr/include/c++/10/bits/specfun.h:45,
                 from /usr/include/c++/10/cmath:1927,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from examination.cpp:2:
/usr/include/c++/10/type_traits:1368:65: error: template argument 1 is invalid
 1368 |     : public integral_constant<std::size_t, 1 + rank<_Tp>::value> { };
      |                                                                 ^
/usr/include/c++/10/type_traits:1368:65: note: invalid template non-type parameter
/usr/include/c++/10/type_traits:1373:37: error: 'size_t' is not a member of 'std'; did you mean 'size_t'?
 1373 |     : public integral_constant<std::size_t, 0> { };
      |                                     ^~~~~~
In file included from /usr/include/stdlib.h:31,
                 from /usr/include/c++/10/bits/std_abs.h:38,
                 from /usr/include/c++/10/cmath:47,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from examination.cpp:2:
/usr/lib/gcc/x86_64-linux-gnu/10/include/stddef.h:209:23: note: 'size_t' declared here
  209 | typedef __SIZE_TYPE__ size_t;
      |                       ^~~~~~
In file included from /usr/include/c++/10/bits/move.h:57,
                 from /usr/include/c++/10/bits/stl_pair.h:59,
                 from /usr/include/c++/10/bits/stl_algobase.h:64,
                 from /usr/include/c++/10/bits/specfun.h:45,
                 from /usr/include/c++/10/cmath:1927,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from examination.cpp:2:
/usr/include/c++/10/type_traits:1373:46: error: template argument 1 is invalid
 1373 |     : public integral_constant<std::size_t, 0> { };
      |                                              ^
/usr/include/c++/10/type_traits:1373:46: note: invalid template non-type parameter
/usr/include/c++/10/type_traits:1375:42: error: 'std::size_t' has not been declared
 1375 |   template<typename _Tp, unsigned _Uint, std::size_t _Size>
      |                                          ^~~
/usr/include/c++/10/type_traits:1376:23: error: '_Size' was not declared in this scope
 1376 |     struct extent<_Tp[_Size], _Uint>
      |                       ^~~~~
/usr/include/c++/10/type_traits:1376:36: error: template argument 1 is invalid
 1376 |     struct extent<_Tp[_Size], _Uint>
      |                                    ^
/usr/include/c++/10/type_traits:1377:37: error: 'size_t' is not a member of 'std'; did you mean 'size_t'?
 1377 |     : public integral_constant<std::size_t,
      |                                     ^~~~~~
In file included from /usr/include/stdlib.h:31,
                 from /usr/include/c++/10/bits/std_abs.h:38,
                 from /usr/include/c++/10/cmath:47,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from examination.cpp:2:
/usr/lib/gcc/x86_64-linux-gnu/10/include/stddef.h:209:23: note: 'size_t' declared here
  209 | typedef __SIZE_TYPE__ size_t;
      |                       ^~~~~~
In file included from /usr/include/c++/10/bits/move.h:57,
                 from /usr/include/c++/10/bits/stl_pair.h:59,
                 from /usr/include/c++/10/bits/stl_algobase.h:64,
                 from /usr/include/c++/10/bits/specfun.h:45,
                 from /usr/include/c++/10/cmath:1927,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from examination.cpp:2:
/usr/include/c++/10/type_traits:1378:24: error: '_Size' was not declared in this scope
 1378 |           _Uint == 0 ? _Size : extent<_Tp,
      |                        ^~~~~
/usr/include/c++/10/type_traits:1379:28: error: template argument 1 is invalid
 1379 |           _Uint - 1>::value>
      |                            ^
/usr/include/c++/10/type_traits:1379:28: note: invalid template non-type parameter
/usr/include/c++/10/type_traits:1384:37: error: 'size_t' is not a member of 'std'; did you mean 'size_t'?
 1384 |     : public integral_constant<std::size_t,
      |                                     ^~~~~~
In file included from /usr/include/stdlib.h:31,
                 from /usr/include/c++/10/bits/std_abs.h:38,
                 from /usr/include/c++/10/cmath:47,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from examination.cpp:2:
/usr/lib/gcc/x86_64-linux-gnu/10/include/stddef.h:209:23: note: 'size_t' declared here
  209 | typedef __SIZE_TYPE__ size_t;
      |                       ^~~~~~
In file included from /usr/include/c++/10/bits/move.h:57,
                 from /usr/include/c++/10/bits/stl_pair.h:59,
                 from /usr/include/c++/10/bits/stl_algobase.h:64,
                 from /usr/include/c++/10/bits/specfun.h:45,
                 from /usr/include/c++/10/cmath:1927,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from examination.cpp:2:
/usr/include/c++/10/type_traits:1386:31: error: template argument 1 is invalid
 1386 |              _Uint - 1>::value>
      |                               ^
/usr/include/c++/10/type_traits:1386:31: note: invalid template non-type parameter
/usr/include/c++/10/type_traits:1975:26: error: 'std::size_t' has not been declared
 1975 |   template<typename _Tp, std::size_t _Size>
      |                          ^~~
/usr/include/c++/10/type_traits:1976:30: error: '_Size' was not declared in this scope
 1976 |     struct remove_extent<_Tp[_Size]>
      |                              ^~~~~
/usr/include/c++/10/type_traits:1976:36: error: template argument 1 is invalid
 1976 |     struct remove_extent<_Tp[_Size]>
      |                                    ^
/usr/include/c++/10/type_traits:1988:26: error: 'std::size_t' has not been declared
 1988 |   template<typename _Tp, std::size_t _Size>
      |                          ^~~
/usr/include/c++/10/type_traits:1989:35: error: '_Size' was not declared in this scope
 1989 |     struct remove_all_extents<_Tp[_Size]>
      |                                   ^~~~~
/usr/include/c++/10/type_traits:1989:41: error: template argument 1 is invalid
 1989 |     struct remove_all_extents<_Tp[_Size]>
      |                                         ^
/usr/include/c++/10/type_traits:2047:12: error: 'std::size_t' has not been declared
 2047 |   template<std::size_t _Len>
      |            ^~~
/usr/include/c++/10/type_traits:2052:23: error: '_Len' was not declared in this scope
 2052 |  unsigned char __data[_Len];
      |                       ^~~~
/usr/include/c++/10/type_traits:2067:12: error: 'std::size_t' has not been declared
 2067 |   template<std::size_t _Len, std::size_t _Align =
      |            ^~~
/usr/include/c++/10/type_traits:2067:30: error: 'std::size_t' has not been declared
 2067 |   template<std::size_t _Len, std::size_t _Align =
      |                              ^~~
/usr/include/c++/10/type_traits:2068:48: error: '_Len' was not declared in this scope
 2068 |     __alignof__(typename __aligned_storage_msa<_Len>::__type)>
      |                                                ^~~~
/usr/include/c++/10/type_traits:2068:52: error: template argument 1 is invalid
 2068 |     __alignof__(typename __aligned_storage_msa<_Len>::__type)>
      |                                                    ^
/usr/include/c++/10/type_traits:2073:23: error: '_Len' was not declared in this scope
 2073 |  unsigned char __data[_Len];
      |                       ^~~~
/usr/include/c++/10/type_traits:2074:37: error: '_Align' was not declared in this scope
 2074 |  struct __attribute__((__aligned__((_Align)))) { } __align;
      |                                     ^~~~~~
In file included from /usr/include/c++/10/bits/stl_algobase.h:64,
                 from /usr/include/c++/10/bits/specfun.h:45,
                 from /usr/include/c++/10/cmath:1927,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from examination.cpp:2:
/usr/include/c++/10/bits/stl_pair.h:92:12: error: 'std::size_t' has not been declared
   92 |   template<std::size_t...>
      |            ^~~
/usr/include/c++/10/bits/stl_pair.h:449:36: error: 'std::size_t' has not been declared
  449 |       template<typename... _Args1, std::size_t... _Indexes1,
      |                                    ^~~
/usr/include/c++/10/bits/stl_pair.h:450:36: error: 'std::size_t' has not been declared
  450 |                typename... _Args2, std::size_t... _Indexes2>
      |                                    ^~~
/usr/include/c++/10/bits/stl_pair.h:453:27: error: '_Indexes1' was not declared in this scope
  453 |              _Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>);
      |                           ^~~~~~~~~
/usr/include/c++/10/bits/stl_pair.h:453:36: error: expected parameter pack before '...'
  453 |              _Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>);
      |                                    ^~~
/usr/include/c++/10/bits/stl_pair.h:453:39: error: template argument 1 is invalid
  453 |              _Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>);
      |                                       ^
/usr/include/c++/10/bits/stl_pair.h:453:55: error: '_Indexes2' was not declared in this scope
  453 |              _Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>);
      |                                                       ^~~~~~~~~
/usr/include/c++/10/bits/stl_pair.h:453:64: error: expected parameter pack before '...'
  453 |              _Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>);
      |                                                                ^~~
/usr/include/c++/10/bits/stl_pair.h:453:67: error: template argument 1 is invalid
  453 |              _Index_tuple<_Indexes1...>, _Index_tuple<_Indexes2...>);
      |                                                                   ^
In file included from /usr/include/c++/10/bits/stl_algobase.h:65,
                 from /usr/include/c++/10/bits/specfun.h:45,
                 from /usr/include/c++/10/cmath:1927,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from examination.cpp:2:
/usr/include/c++/10/bits/stl_iterator_base_types.h:125:67: error: 'ptrdiff_t' does not name a type
  125 |   template<typename _Category, typename _Tp, typename _Distance = ptrdiff_t,
      |                                                                   ^~~~~~~~~
In file included from /usr/include/c++/10/bits/stl_algobase.h:65,
                 from /usr/include/c++/10/bits/specfun.h:45,
                 from /usr/include/c++/10/cmath:1927,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from examination.cpp:2:
/usr/include/c++/10/bits/stl_iterator_base_types.h:1:1: note: 'ptrdiff_t' is defined in header '<cstddef>'; did you forget to '#include <cstddef>'?
  +++ |+#include <cstddef>
    1 | // Types used in iterator implementation -*- C++ -*-
In file included from /usr/include/c++/10/bits/stl_algobase.h:65,
                 from /usr/include/c++/10/bits/specfun.h:45,
                 from /usr/include/c++/10/cmath:1927,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from examination.cpp:2:
/usr/include/c++/10/bits/stl_iterator_base_types.h:214:15: error: 'ptrdiff_t' does not name a type
  214 |       typedef ptrdiff_t                   difference_type;
      |               ^~~~~~~~~
/usr/include/c++/10/bits/stl_iterator_base_types.h:214:15: note: 'ptrdiff_t' is defined in header '<cstddef>'; did you forget to '#include <cstddef>'?
/usr/include/c++/10/bits/stl_iterator_base_types.h:225:15: error: 'ptrdiff_t' does not name a type
  225 |       typ