제출 #1048945

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1048945		Alihan_8	모임들 (IOI18_meetings)	C++17	컴파일 에러	0 ms	0 KiB

meetings

786432 KB	#include "meetings.h"

#include <bits/stdc++.h>

using namespace std;

#define all(x) x.begin(), x.end()
#define ar array
#define pb push_back
#define ln '\n'
//#define int long long

using i64 = long long;

template <class F, class _S>
bool chmin(F &u, const _S &v){
    bool flag = false;
    if ( u > v ){
        u = v; flag |= true;
    }
    return flag;
}

template <class F, class _S>
bool chmax(F &u, const _S &v){
    bool flag = false;
    if ( u < v ){
        u = v; flag |= true;
    }
    return flag;
}

const i64 inf = 1e15;

const int N = 1e5 + 1;

int n;

struct SegTree{
	struct Info{
		i64 dp[21][21];
		
		vector <ar<int,2>> ls, rs;
		
		Info(){
			for ( int i = 0; i <= 20; i++ ){
				for ( int j = 0; j <= 20; j++ ){
					dp[i][j] = inf;
				}
			}
 			
			ls.pb({0, 0});
			rs.pb({0, 0});
		}
	};
	
	vector <Info> T;
	
	void modify(int n){ T.resize(n * 4 + 5); }
		
	void merge(Info &rt, const Info &lf, const Info &rg){
		rt = Info();
		
		rt.ls = lf.ls;
		for ( auto &[h, v]: rg.ls ){
			if ( rt.ls.back()[0] < h ){
				rt.ls.pb({h, v});
			} else rt.ls.back()[1] += v;
		}
		
		rt.rs = rg.rs;
		for ( auto &[h, v]: lf.rs ){
			if ( rt.rs.back()[0] < h ){
				rt.rs.pb({h, v});
			} else rt.rs.back()[1] += v;
		}
		
		for ( int x = 0; x <= 20; x++ ){
			i64 cnt = 0, pf = 0;
			
			for ( auto &[h, v]: rg.ls ){
				cnt += h * 1LL * v;
			}
			
			int j = 0;
			
			for ( int y = 0; y <= 20; y++ ){
				int r = max(y, rg.ls.back()[0]);
				
				cnt += pf;
				
				while ( j < (int)rg.ls.size() && rg.ls[j][0] <= y ){
					auto &[h, v] = rg.ls[j++];
					
					cnt += (y - h) * 1LL * v;
					pf += v;
				}
				
				chmin(rt.dp[x][r], lf.dp[x][y] + cnt);
			}
		}
		
		for ( int y = 0; y <= 20; y++ ){
			i64 cnt = 0, pf = 0;
			
			for ( auto &[h, v]: lf.rs ){
				cnt += h * 1LL * v;
			}
			
			int j = 0;
			
			for ( int x = 0; x <= 20; x++ ){
				int l = max(x, lf.rs.back()[0]);
				
				cnt += pf;
				
				while ( j < (int)lf.rs.size() && lf.rs[j][0] <= x ){
					auto &[h, v] = lf.rs[j++];
					
					cnt += (x - h) * 1LL * v;
					pf += v;
				}
				
				chmin(rt.dp[l][y], rg.dp[x][y] + cnt);
			}
		}
	}
	
	void upd(int v, int l, int r, int p, int x){
		if ( l == r ){
			T[v].dp[x][x] = x;
			T[v].ls.pb({x, 1});
			T[v].rs.pb({x, 1});
			
			return;
		}
		
		int m = (l + r) / 2;
		
		if ( p <= m ) upd(v * 2, l, m, p, x);
		else  upd(v * 2 + 1, m + 1, r, p, x);
		
		merge(T[v], T[v * 2], T[v * 2 + 1]);
	}
	
	void upd(int p, int x){ upd(1, 0, n - 1, p, x); }	
	
	Info get(int v, int l, int r, int tl, int tr){
		Info ret;
		
		if ( l > tr or r < tl ) return ret;
		
		if ( tl <= l && tr >= r ){
			return T[v];
		}
		
		int m = (l + r) / 2;
		
		if ( m < tl ) return get(v * 2 + 1, m + 1, r, tl, tr);
		
		if ( m + 1 > tr ) return get(v * 2, l, m, tl, tr);
		
		merge(ret, get(v * 2, l, m, tl, tr), get(v * 2 + 1, m + 1, r, tl, tr));
		
		return ret;
	} 
	
	i64 qry(int l, int r){
		Info q = get(1, 0, n - 1, l, r);
		
		i64 opt = inf;
		
		for ( int x = 0; x <= 20; x++ ){
			for ( int y = 0; y <= 20; y++ ){
				chmin(opt, q.dp[x][y]);
			}
		}
		
		return opt;
	};
} seg;

std::vector<long long> minimum_costs(std::vector<int> H, std::vector<int> L,
                                     std::vector<int> R) {
	int q = L.size(); n = H.size(); 
	
	// subtask #4
	
	seg.modify(n);
	
	for ( int i = 0; i < n; i++ ){
		seg.upd(i, H[i]);
	}
	
	vector <i64> ans(q);
	
	for ( int i = 0; i < q; i++ ){
		ans[i] = seg.qry(L[i], R[i]);
	}
	
	return ans;
}

컴파일 시 표준 에러 (stderr) 메시지

meetings.cpp:1:11: error: stray '#' in program
    1 | 786432 KB #include "meetings.h"
      |           ^
meetings.cpp:1:1: error: expected unqualified-id before numeric constant
    1 | 786432 KB #include "meetings.h"
      | ^~~~~~
In file included from /usr/include/c++/10/cmath:43,
                 from /usr/include/x86_64-linux-gnu/c++/10/bits/stdc++.h:41,
                 from meetings.cpp:3:
/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 meetings.cpp:3:
/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 meetings.cpp:3:
/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 meetings.cpp:3:
/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 meetings.cpp:3:
/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 meetings.cpp:3:
/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 meetings.cpp:3:
/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 meetings.cpp:3:
/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 meetings.cpp:3:
/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 meetings.cpp:3:
/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 meetings.cpp:3:
/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 meetings.cpp:3:
/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 meetings.cpp:3:
/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 meetings.cpp:3:
/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 meetings.cpp:3:
/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 meetings.cpp:3:
/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 meetings.cpp:3:
/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 meetings.cpp:3:
/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 meetings.cpp:3:
/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 meetings.cpp:3:
/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