Language: C++

#include <bits/stdc++.h>
typedef long long LL;
#define SORT(c) sort((c).begin(),(c).end())
 
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)
 
using namespace std;
int main(void)
{
  int n;
  string s;
  cin >> n >> s;
  int dp[1048576];
  pair<int, int> dp10[1048576];
  pair<int, int> dp11[1048576];// potential, already
  dp[0]=0;
  dp10[0]=make_pair(-1048576,-1048576);
  dp11[0]=make_pair(0,0);
  REP(i,n){
    if(s[i] == '0') {
      dp[i+1] = dp[i];
      dp10[i+1] = dp11[i];
      dp11[i+1] = make_pair(dp[i],0);
    }else{
      dp[i+1] = max(dp[i], dp10[i].first);
      dp10[i+1] = (dp10[i].second+2, dp10[i].second+1);
      dp11[i+1] = make_pair(dp11[i].first+1,dp11[i].second);
    }
  }
  cout << dp[n] << endl;
  return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:27:54: error: no match for 'operator=' (operand types are 'std::pair<int, int>' and 'int')
   27 |       dp10[i+1] = (dp10[i].second+2, dp10[i].second+1);
      |                                                      ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 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_pair.h:946:9: note: candidate: 'template<class _U1, class _U2> typename std::enable_if<std::__and_<std::is_assignable<_T1&, const _U1&>, std::is_assignable<_T2&, const _U2&> >::value, std::pair<_T1, _T2>&>::type std::pair<_T1, _T2>::operator=(const std::pair<_U1, _U2>&) [with _U2 = _U1; _T1 = int; _T2 = int]'
  946 |         operator=(const pair<_U1, _U2>& __p)
      |         ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:946:9: note:   template argument deduction/substitution failed:
a.cc:27:54: note:   mismatched types 'const std::pair<_T1, _T2>' and 'int'
   27 |       dp10[i+1] = (dp10[i].second+2, dp10[i].second+1);
      |                                                      ^
/usr/include/c++/14/bits/stl_pair.h:957:9: note: candidate: 'template<class _U1, class _U2> typename std::enable_if<std::__and_<std::is_assignable<_T1&, _U1&&>, std::is_assignable<_T2&, _U2&&> >::value, std::pair<_T1, _T2>&>::type std::pair<_T1, _T2>::operator=(std::pair<_U1, _U2>&&) [with _U2 = _U1; _T1 = int; _T2 = int]'
  957 |         operator=(pair<_U1, _U2>&& __p)
      |         ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:957:9: note:   template argument deduction/substitution failed:
a.cc:27:54: note:   mismatched types 'std::pair<_T1, _T2>' and 'int'
   27 |       dp10[i+1] = (dp10[i].second+2, dp10[i].second+1);
      |                                                      ^
/usr/include/c++/14/bits/stl_pair.h:921:7: note: candidate: 'std::pair<_T1, _T2>& std::pair<_T1, _T2>::operator=(std::__conditional_t<((bool)std::__and_<std::is_copy_assignable<_T1>, std::is_copy_assignable<_T2> >::value), const std::pair<_T1, _T2>&, const std::__nonesuch&>) [with _T1 = int; _T2 = int; std::__conditional_t<((bool)std::__and_<std::is_copy_assignable<_T1>, std::is_copy_assignable<_T2> >::value), const std::pair<_T1, _T2>&, const std::__nonesuch&> = const std::pair<int, int>&]'
  921 |       operator=(__conditional_t<__and_<is_copy_assignable<_T1>,
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:923:65: note:   no known conversion for argument 1 from 'int' to 'std::__conditional_t<true, const std::pair<int, int>&, const std::__nonesuch&>' {aka 'const std::pair<int, int>&'}
  921 |       operator=(__conditional_t<__and_<is_copy_assignable<_T1>,
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  922 |                                        is_copy_assignable<_T2>>::value,
      |                                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  923 |                                 const pair&, const __nonesuch&> __p)
      |                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_pair.h:931:7: note: candidate: 'std::pair<_T1, _T2>& std::pair<_T1, _T2>::operator=(std::__conditional_t<((bool)std::__and_<std::is_move_assignable<_Tp>, std::is_move_assignable<_T2> >::value), std::pair<_T1, _T2>&&, std::__nonesuch&&>) [with _T1 = int; _T2 = int; std::__conditional_t<((bool)std::__and_<std::is_move_assignable<_Tp>, std::is_move_assignable<_T2> >::value), std::pair<_T1, _T2>&&, std::__nonesuch&&> = std::pair<int, int>&&]'
  931 |       operator=(__conditional_t<__and_<is_move_assignable<_T1>,
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:933:55: note:   no known conversion for argument 1 from 'int' to 'std::__conditional_t<true, std::pair<int, int>&&, std::__nonesuch&&>' {aka 'std::pair<int, int>&&'}
  931 |       operator=(__conditional_t<__and_<is_move_assignable<_T1>,
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  932 |                                        is_move_assignable<_T2>>::value,
      |                                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  933 |                                 pair&&, __nonesuch&&> __p)
      |                                 ~~~~~~~~~~~~~~~~~~~~~~^~~