Language: C++

#include<bits/stdc++.h>
using namespace std;
 int a[1000000][4];
int dp[1000000][4];
int solve(int n, int i){
  if(n==0)
    return 0;
  if(dp[n]!= -1)
    return dp[n];
  
  for(int j=1;j<=3;j++){
    if(i!=j)
    dp[n]=max(dp[n], solve(n-1,j)+a[n][j]);
  }
  return dp[n]
}
int main(){
  int n;
  cin>> n;
  
   // int a[n][3];
  memset(dp,-1,sizeof(dp));
    for(int i=1;i<=n;i++){
      for(int j=1;j<=3;j++)
        cin>> a[i][j];
    }
      cout<<solve(n,0);
      
}


Compiler output:
a.cc: In function 'int solve(int, int)':
a.cc:8:11: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]
    8 |   if(dp[n]!= -1)
      |      ~~~~~^~~~~
a.cc:9:16: error: invalid conversion from 'int*' to 'int' [-fpermissive]
    9 |     return dp[n];
      |            ~~~~^
      |                |
      |                int*
a.cc:13:14: error: no matching function for call to 'max(int [4], int)'
   13 |     dp[n]=max(dp[n], solve(n-1,j)+a[n][j]);
      |           ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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:13:14: note:   deduced conflicting types for parameter 'const _Tp' ('int [4]' and 'int')
   13 |     dp[n]=max(dp[n], solve(n-1,j)+a[n][j]);
      |           ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/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:13:14: note:   mismatched types 'std::initializer_list<_Tp>' and 'int*'
   13 |     dp[n]=max(dp[n], solve(n-1,j)+a[n][j]);
      |           ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
a.cc:15:14: error: invalid conversion from 'int*' to 'int' [-fpermissive]
   15 |   return dp[n]
      |          ~~~~^
      |              |
      |              int*
a.cc:15:15: error: expected ';' before '}' token
   15 |   return dp[n]
      |               ^
      |               ;
   16 | }
      | ~