Language: C++

#include<iostream>
#include<string>
#include <vector>
#include<stack>
#include<queue>
#include<map>
#include<algorithm>
#include<iomanip>
#include<cmath>
#include<bitset>
using namespace std;
using vi = vector<int>;
using vii = vector<vi>;
using vs = vector<string>;
using pii = pair<int, int>;
#define rep(i,n) for(int i=0;i<n;i++)
#define rep2(i,m,n) for(int i=m;i<n;i++)
#define vsort(v) sort(v.begin(), v.end())
#define rv(v) reverse(v.begin(), v.end())
#define ll long long
#define PI 3.141592653589793
using vll = vector<ll>;
using Graph = vii;
const ll MOD = 1e9 + 7;

int main() {
	ll n, k;
	cin >> n >> k;
	vi p(n);
	rep(i, n) cin >> p[i];
	vector<double> e(n);
	rep(i, n) {
		double q = p[i];
		double ex = p * (p + 1.0) / 2.0;
		e[i] = ex;
	}
	for (ll i = 1; i < n; i++) {
		e[i] = e[i] + e[i - 1];
	}
	double ans = 0;
	for (int i = 0; i < n - k; i++) {
		double t = e[i + k] - e[i];
		if (t > ans) ans = t;
	}
	cout << setprecision(7) << ans << endl;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:34:36: error: no match for 'operator+' (operand types are 'vi' {aka 'std::vector<int>'} and 'double')
   34 |                 double ex = p * (p + 1.0) / 2.0;
      |                                  ~ ^ ~~~
      |                                  |   |
      |                                  |   double
      |                                  vi {aka std::vector<int>}
In file included from /usr/include/c++/14/string:48,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_iterator.h:627:5: note: candidate: 'template<class _Iterator> constexpr std::reverse_iterator<_Iterator> std::operator+(typename reverse_iterator<_Iterator>::difference_type, const reverse_iterator<_Iterator>&)'
  627 |     operator+(typename reverse_iterator<_Iterator>::difference_type __n,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:627:5: note:   template argument deduction/substitution failed:
a.cc:34:38: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'double'
   34 |                 double ex = p * (p + 1.0) / 2.0;
      |                                      ^~~
/usr/include/c++/14/bits/stl_iterator.h:1798:5: note: candidate: 'template<class _Iterator> constexpr std::move_iterator<_IteratorL> std::operator+(typename move_iterator<_IteratorL>::difference_type, const move_iterator<_IteratorL>&)'
 1798 |     operator+(typename move_iterator<_Iterator>::difference_type __n,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1798:5: note:   template argument deduction/substitution failed:
a.cc:34:38: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'double'
   34 |                 double ex = p * (p + 1.0) / 2.0;
      |                                      ^~~
In file included from /usr/include/c++/14/string:54:
/usr/include/c++/14/bits/basic_string.h:3598:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3598 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3598:5: note:   template argument deduction/substitution failed:
a.cc:34:38: note:   'vi' {aka 'std::vector<int>'} is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   34 |                 double ex = p * (p + 1.0) / 2.0;
      |                                      ^~~
/usr/include/c++/14/bits/basic_string.h:3616:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const _CharT*, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3616 |     operator+(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3616:5: note:   template argument deduction/substitution failed:
a.cc:34:38: note:   mismatched types 'const _CharT*' and 'std::vector<int>'
   34 |                 double ex = p * (p + 1.0) / 2.0;
      |                                      ^~~
/usr/include/c++/14/bits/basic_string.h:3635:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(_CharT, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3635 |     operator+(_CharT __lhs, const basic_string<_CharT,_Traits,_Alloc>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3635:5: note:   template argument deduction/substitution failed:
a.cc:34:38: note:   mismatched types 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'double'
   34 |                 double ex = p * (p + 1.0) / 2.0;
      |                                      ^~~
/usr/include/c++/14/bits/basic_string.h:3652:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const _CharT*)'
 3652 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3652:5: note:   template argument deduction/substitution failed:
a.cc:34:38: note:   'vi' {aka 'std::vector<int>'} is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   34 |                 double ex = p * (p + 1.0) / 2.0;
      |                                      ^~~
/usr/include/c++/14/bits/basic_string.h:3670:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, _CharT)'
 3670 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs, _CharT __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3670:5: note:   template argument deduction/substitution failed:
a.cc:34:38: note:   'vi' {aka 'std::vector<int>'} is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   34 |                 double ex = p * (p + 1.0) / 2.0;
      |                                      ^~~
/usr/include/c++/14/bits/basic_string.h:3682:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3682 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3682:5: note:   template argument deduction/substitution failed:
a.cc:34:38: note:   'vi' {aka 'std::vector<int>'} is not derived from 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   34 |                 double ex = p * (p + 1.0) / 2.0;
      |                                      ^~~
/usr/include/c++/14/bits/basic_string.h:3689:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3689 |     operator+(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3689:5: note:   template argument deduction/substitution failed:
a.cc:34:38: note:   'vi' {aka 'std::vector<int>'} is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   34 |                 double ex = p * (p + 1.0) / 2.0;
      |                                      ^~~
/usr/include/c++/14/bits/basic_string.h:3696:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3696 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3696:5: note:   template argument deduction/substitution failed:
a.cc:34:38: note:   'vi' {aka 'std::vector<int>'} is not derived from 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   34 |                 double ex = p * (p + 1.0) / 2.0;
      |                                      ^~~
/usr/include/c++/14/bits/basic_string.h:3719:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(const _CharT*, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3719 |     operator+(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3719:5: note:   template argument deduction/substitution failed:
a.cc:34:38: note:   mismatched types 'const _CharT*' and 'std::vector<int>'
   34 |                 double ex = p * (p + 1.0) / 2.0;
      |                                      ^~~
/usr/include/c++/14/bits/basic_string.h:3726:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(_CharT, __cxx11::basic_string<_CharT, _Traits, _Allocator>&&)'
 3726 |     operator+(_CharT __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3726:5: note:   template argument deduction/substitution failed:
a.cc:34:38: note:   mismatched types 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'double'
   34 |                 double ex = p * (p + 1.0) / 2.0;
      |                                      ^~~
/usr/include/c++/14/bits/basic_string.h:3733:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, const _CharT*)'
 3733 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3733:5: note:   template argument deduction/substitution failed:
a.cc:34:38: note:   'vi' {aka 'std::vector<int>'} is not derived from 'std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   34 |                 double ex = p * (p + 1.0) / 2.0;
      |                                      ^~~
/usr/include/c++/14/bits/basic_string.h:3740:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> std::__cxx11::basic_string<_CharT, _Traits, _Allocator> std::operator+(__cxx11::basic_string<_CharT, _Traits, _Allocator>&&, _CharT)'
 3740 |     operator+(basic_string<_CharT, _Traits, _Alloc>&& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3740:5: note:   template argument deduction/substitution failed:
a.cc:34:38: note:   'vi' {aka 'std::vector<int>'} is not derived from 'std::__cxx11: