Language: C++

#include<bits/stdc++.h>
using namespace std;

using Lint=long long;
template<int mod> class ModInt
{   
 private:
    Lint val;
 public:
    Lint value(){ return val; }
    ModInt(Lint x=0){ val=x%mod; }
    ModInt pow(int n){
        ModInt res(1),x(val);
        while(n>0){ if(n&1) res*=x; x*=x; n>>=1; }
        return res;
    }
    ModInt inv(){ return pow(mod-2); }
    ModInt& operator+=(ModInt rhs){ val+=rhs.val; if(val>=mod) val-=mod; return *this; }
    ModInt& operator-=(ModInt rhs){ val+=mod-rhs.val; if(val>=mod) val-=mod; return *this; }
    ModInt& operator*=(ModInt rhs){ val=val*rhs.val%mod; return *this; }
    ModInt& operator/=(ModInt rhs){ *this*=rhs.inv(); return *this; }
    ModInt operator+(ModInt rhs){ return ModInt(val)+=rhs; }
    ModInt operator-(ModInt rhs){ return ModInt(val)-=rhs; }
    ModInt operator*(ModInt rhs){ return ModInt(val)*=rhs; }
    ModInt operator/(ModInt rhs){ return ModInt(val)/=rhs; }
};
using mint=ModInt<1000000007>;

mint dp[310][310][310];

int main()
{
    int N; cin>>N;
    string s; cin>>s;
    assert(N<=300);
    dp[0][0][0]=1;
    for(int i=0;i<N;i++) for(int j=0;j<=i;j++) for(int k=0;k<=j;k++){
        if(dp[i][j][k]==0) continue;
        if(j>k){
            dp[i+1][j+1][k]+=dp[i][j][k]; // insert 0
            dp[i+1][j+1][k]+=dp[i][j][k]; // insert 1
            dp[i+1][j-1][k]+=dp[i][j][k]; // erase
        }else{
            if(s[j]=='0') dp[i+1][j+1][j+1]+=dp[i][j][j];
            else dp[i+1][j+1][j]+=dp[i][j][j];
            if(s[j]=='1') dp[i+1][j+1][j+1]+=dp[i][j][j];
            else dp[i+1][j+1][j]+=dp[i][j][j];
            dp[i+1][max(0,j-1)][max(0,j-1)]+=dp[i][j][j];
        }
    }
    cout<<dp[N][s.size()][s.size()].value()<<endl;
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:38:23: error: no match for 'operator==' (operand types are 'mint' {aka 'ModInt<1000000007>'} and 'int')
   38 |         if(dp[i][j][k]==0) continue;
      |            ~~~~~~~~~~~^~~
      |                      |  |
      |                      |  int
      |                      mint {aka ModInt<1000000007>}
In file included from /usr/include/c++/14/regex:68,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:181,
                 from a.cc:1:
/usr/include/c++/14/bits/regex.h:1103:5: note: candidate: 'template<class _BiIter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const sub_match<_BiIter>&)'
 1103 |     operator==(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1103:5: note:   template argument deduction/substitution failed:
a.cc:38:25: note:   'mint' {aka 'ModInt<1000000007>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   38 |         if(dp[i][j][k]==0) continue;
      |                         ^
/usr/include/c++/14/bits/regex.h:1199:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator==(__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&, const sub_match<_BiIter>&)'
 1199 |     operator==(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1199:5: note:   template argument deduction/substitution failed:
a.cc:38:25: note:   'mint' {aka 'ModInt<1000000007>'} is not derived from 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>'
   38 |         if(dp[i][j][k]==0) continue;
      |                         ^
/usr/include/c++/14/bits/regex.h:1274:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator==(const sub_match<_BiIter>&, __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&)'
 1274 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1274:5: note:   template argument deduction/substitution failed:
a.cc:38:25: note:   'mint' {aka 'ModInt<1000000007>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   38 |         if(dp[i][j][k]==0) continue;
      |                         ^
/usr/include/c++/14/bits/regex.h:1366:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const typename std::iterator_traits<_Iter>::value_type*, const sub_match<_BiIter>&)'
 1366 |     operator==(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1366:5: note:   template argument deduction/substitution failed:
a.cc:38:25: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
   38 |         if(dp[i][j][k]==0) continue;
      |                         ^
/usr/include/c++/14/bits/regex.h:1441:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)'
 1441 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1441:5: note:   template argument deduction/substitution failed:
a.cc:38:25: note:   'mint' {aka 'ModInt<1000000007>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   38 |         if(dp[i][j][k]==0) continue;
      |                         ^
/usr/include/c++/14/bits/regex.h:1534:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const typename std::iterator_traits<_Iter>::value_type&, const sub_match<_BiIter>&)'
 1534 |     operator==(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1534:5: note:   template argument deduction/substitution failed:
a.cc:38:25: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
   38 |         if(dp[i][j][k]==0) continue;
      |                         ^
/usr/include/c++/14/bits/regex.h:1613:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator==(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)'
 1613 |     operator==(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1613:5: note:   template argument deduction/substitution failed:
a.cc:38:25: note:   'mint' {aka 'ModInt<1000000007>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   38 |         if(dp[i][j][k]==0) continue;
      |                         ^
/usr/include/c++/14/bits/regex.h:2186:5: note: candidate: 'template<class _Bi_iter, class _Alloc> bool std::__cxx11::operator==(const match_results<_BiIter, _Alloc>&, const match_results<_BiIter, _Alloc>&)'
 2186 |     operator==(const match_results<_Bi_iter, _Alloc>& __m1,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:2186:5: note:   template argument deduction/substitution failed:
a.cc:38:25: note:   'mint' {aka 'ModInt<1000000007>'} is not derived from 'const std::__cxx11::match_results<_BiIter, _Alloc>'
   38 |         if(dp[i][j][k]==0) continue;
      |                         ^
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:
/usr/include/c++/14/bits/stl_pair.h:1033:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator==(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1033 |     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1033:5: note:   template argument deduction/substitution failed:
a.cc:38:25: note:   'mint' {aka 'ModInt<1000000007>'} is not derived from 'const std::pair<_T1, _T2>'
   38 |         if(dp[i][j][k]==0) continue;
      |                         ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:441:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  441 |     operator==(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:441:5: note:   template argument deduction/substitution failed:
a.cc:38:25: note:   'mint' {aka 'ModInt<1000000007>'} is not derived from 'const std::reverse_iterator<_Iterator>'
   38 |         if(dp[i][j][k]==0) continue;
      |                         ^
/usr/include/c++/14/bits/stl_iterator.h:486:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  486 |     operator==(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:486:5: note:   template argument deduction/substitution failed:
a.cc:38:25: note:   'mint' {aka 'ModInt<1000000007>'} is not derived from 'const std::reverse_iterator<_Iterator>'
   38 |         if(dp[i][j][k]==0) continue;
      |                         ^
/usr/include/c++/14/bits/stl_iterator.h:1667:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator==(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1667 |     operator==(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1667:5: note:   template argument deduction/substitution failed:
a.cc:38:25: note:   'mint' {aka 'ModInt<1000000007>'} is not derived from 'const std::move_iterator<_IteratorL>'
   38 |         if(dp[i][j][k]==0) continue;
      |                         ^
/usr/include/c++/14/bits/stl_iterator.h:1737:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator==(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1737 |     operator==(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1737:5: note:   template argument deduction/substitution failed:
a.cc:38:25: note:   'mint' {aka 'ModInt<1000000007>'} is not derived from 'const std::move_iterator<_IteratorL>'
   38 |         if(dp[i][j][k]==0) continue;
      |                         ^
In file included from /usr/include/c++/14/bits/char_traits.h:42,
                 from /usr/include/c++/14/string:42,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/usr/include/c++/14/bits/postypes.h:192:5: note: candidate: 'template<class _StateT> bool std::operator==(const fpos<_StateT>&, const fpos<_StateT>&)'
  192 |     operator==(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/postypes.h:192:5: note:   template argument deduction/substitution failed:
a.cc:38:25: note:   'mint' {aka 'ModInt<1000000007>'} is not derived from 'const std::fpos<_StateT>'
   38 |         if(dp[i][j][k]==0) continue;
      |                         ^
In file included from /usr/include/c++/14/string:43:
/usr/include/c++/14/bits/allocator.h:235:5: note: candidate: 'template<class _T1, class _T2> bool std::operator==(const allocator<_CharT>&, const allocator<_T2>&)'
  235 |     operator==(const allocator<_T1>&, const allocator<_T2>&)
      |     ^~~~~~~~
/usr/include/c++/14/bits/allocator.h:235:5: note:   template argument deduction/substitution failed:
a.cc:38:25: note:   'mint' {aka 'ModInt<1000000007>'} is not derived from 'const std::allocator<_CharT>'
   38 |         if(dp[i][j][k]==0) continue;
      |                         ^
In file included from /usr/include/c++/14/bits/basic_string.h:47,
                 from /usr/include/c++/14/string:54:
/usr/include/c++/14/string_view:629:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator==(basic_string_view<_CharT, _Traits>, __type_identity_t<basic_string_view<_CharT, _Traits> >)'
  629 |     operator==(basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:629:5: note:   template argument deduction/substi