Language: C++

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef vector<ll> vl ;
typedef vector<int> vi;
typedef pair<int, int> pi;
typedef pair<ll,ll> pl;

#define rep(i,N) for(int i=0; i < (int)N; i++)
#define all(v) (v).begin(),(v).end()

const int INF = 100000002;

int main(){
	int n; cin >> n;
	vl a(n); rep(i,n) cin >> a[i];
	vector<vector<vl>> dp(n+1, vector<vl>(2, vl(3, -INF)));
	rep(i,2)rep(j,3)dp[0][i][j] = 0;

	rep(i,n)rep(j,2)rep(k,3){
		if(k+j<3) dp[i+1][1][k+j] = max(dp[i][j][k], dp[i+1][1][k+j]);
		
		//if(j) dp[i+1][0][k] = max(dp[i][j][k]+a[i], dp[i+1][0][k]);
		if(j){
			if (i==n-1 && k==0){
				continue;	
			}else{
				dp[i+1][0][k] = max(dp[i][j][k]+a[i], dp[i+1][0][k]);	
			
			}
		}
		//cout <<i+1 << " " << j << " "<< dp[i+1][1][2] << " " <<  dp[i+1][0][2] << endl;
	}
	
	if(n%2) cout << max(dp[n][1][1], dp[0][2]);
	else cout << max(dp[n][0][1], dp[n][1][0]); 
}

Compiler output:
a.cc: In function 'int main()':
a.cc:36:28: error: no matching function for call to 'max(__gnu_cxx::__alloc_traits<std::allocator<long long int>, long long int>::value_type&, __gnu_cxx::__alloc_traits<std::allocator<std::vector<long long int> >, std::vector<long long int> >::value_type&)'
   36 |         if(n%2) cout << max(dp[n][1][1], dp[0][2]);
      |                         ~~~^~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_algobase.h:257:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)'
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
a.cc:36:28: note:   deduced conflicting types for parameter 'const _Tp' ('long long int' and '__gnu_cxx::__alloc_traits<std::allocator<std::vector<long long int> >, std::vector<long long int> >::value_type' {aka 'std::vector<long long int>'})
   36 |         if(n%2) cout << max(dp[n][1][1], dp[0][2]);
      |                         ~~~^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)'
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/algorithm:61:
/usr/include/c++/14/bits/stl_algo.h:5706:5: note: candidate: 'template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)'
 5706 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5706:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5716:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)'
 5716 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5716:5: note:   template argument deduction/substitution failed:
a.cc:36:28: note:   mismatched types 'std::initializer_list<_Tp>' and 'long long int'
   36 |         if(n%2) cout << max(dp[n][1][1], dp[0][2]);
      |                         ~~~^~~~~~~~~~~~~~~~~~~~~~~