Language: C++

#include <bits/stdc++.h>
#define rep(i,n) for(int i=0; i<n; i++)
#define PI 3.14159265359
#define INF 1000100100
#define MOD 1000000007
#define all(x) (x).begin(),(x).end()
typedef long long ll;
#define P pair<ll, ll>
using namespace std;

// auto mod int
// https://youtu.be/L8grWxBlIZ4?t=9858
// https://youtu.be/ERZuLAxZffQ?t=4807 : optimize
// https://youtu.be/8uowVvQ_-Mo?t=1329 : division

const int mod = 1000000007;
struct mint {
  ll x; // typedef long long ll;
  mint(ll x=0):x((x%mod+mod)%mod){}
  mint& operator+=(const mint a) {
    if ((x += a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator-=(const mint a) {
    if ((x += mod-a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator*=(const mint a) {
    (x *= a.x) %= mod;
    return *this;
  }
  mint operator+(const mint a) const {
    mint res(*this);
    return res+=a;
  }
  mint operator-(const mint a) const {
    mint res(*this);
    return res-=a;
  }
  mint operator*(const mint a) const {
    mint res(*this);
    return res*=a;
  }
  mint pow(ll t) const {
    if (!t) return 1;
    mint a = pow(t>>1);
    a *= a;
    if (t&1) a *= *this;
    return a;
  }

  // for prime mod
  mint inv() const {
    return pow(mod-2);
  }
  mint& operator/=(const mint a) {
    return (*this) *= a.inv();
  }
  mint operator/(const mint a) const {
    mint res(*this);
    return res/=a;
  }
};
// 出力は.xで！！！！

mint dp[101][16];

int main(){
  int n; cin >> n;
  rep(i,101)rep(k,16) dp[i][k]=0;
  dp[2][0]=1; //AC
  dp[2][1]=1; //GC
  dp[2][2]=1; //TC
  dp[2][3]=1; //CC
  dp[2][4]=1; //CA
  dp[2][5]=1; //GA
  dp[2][6]=1; //TA
  dp[2][7]=1; //AA
  dp[2][8]=1; //AG
  dp[2][9]=1; //CG
  dp[2][10]=1; //TG
  dp[2][11]=1; //GG
  dp[2][12]=1; //AT
  dp[2][13]=1; //CT
  dp[2][14]=1; //GT
  dp[2][15]=1; //TT

  for(int i=3; i<=n; i++){
      dp[i][0]=dp[i-1][4]+dp[i-1][6]+dp[i-1][7];
      dp[i][1]=dp[i-1][9]+dp[i-1][10]+dp[i-1][11];
      dp[i][2]=dp[i-1][12]+dp[i-1][13]+dp[i-1][14]+dp[i-1][15];
      dp[i][3]=dp[i-1][0]+dp[i-1][1]+dp[i-1][2]+dp[i-1][3];
      dp[i][4]=dp[i-1][0]+dp[i-1][1]+dp[i-1][2]+dp[i-1][3];
      dp[i][5]=dp[i-1][8]+dp[i-1][9]+dp[i-1][10]+dp[i-1][11];
      dp[i][6]=dp[i-1][12]+dp[i-1][13]+dp[i-1][14]+dp[i-1][15];
      dp[i][7]=dp[i-1][4]+dp[i-1][5]+dp[i-1][6]+dp[i-1][7];
      dp[i][8]=dp[i-1][4]+dp[i-1][5]+dp[i-1][6]+dp[i-1][7];
      dp[i][9]=dp[i-1][1]+dp[i-1][2]+dp[i-1][3];
      dp[i][10]=dp[i-1][12]+dp[i-1][13]+dp[i-1][14]+dp[i-1][15];
      dp[i][11]=dp[i-1][8]+dp[i-1][9]+dp[i-1][10]+dp[i-1][11];
      dp[i][12]=dp[i-1][4]+dp[i-1][5]+dp[i-1][6]+dp[i-1][7];
      dp[i][13]=dp[i-1][0]+dp[i-1][1]+dp[i-1][2]+dp[i-1][3];
      dp[i][14]=dp[i-1][8]+dp[i-1][9]+dp[i-1][10]+dp[i-1][11];
      dp[i][15]=dp[i-1][12]+dp[i-1][13]+dp[i-1][14]+dp[i-1][15];
    }
  mint ans=0;
  rep(i,16){
    ans+=dp[n][i];
  }
  while(ans<0) ans+=MOD;
  cout << ans.x << endl;
return 0;
}


Compiler output:
a.cc: In function 'int main()':
a.cc:110:12: error: no match for 'operator<' (operand types are 'mint' and 'int')
  110 |   while(ans<0) ans+=MOD;
      |         ~~~^~
      |         |   |
      |         |   int
      |         mint
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:1143:5: note: candidate: 'template<class _BiIter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const sub_match<_BiIter>&)'
 1143 |     operator<(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1143:5: note:   template argument deduction/substitution failed:
a.cc:110:13: note:   'mint' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
  110 |   while(ans<0) ans+=MOD;
      |             ^
/usr/include/c++/14/bits/regex.h:1224:5: 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>&)'
 1224 |     operator<(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1224:5: note:   template argument deduction/substitution failed:
a.cc:110:13: note:   'mint' is not derived from 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>'
  110 |   while(ans<0) ans+=MOD;
      |             ^
/usr/include/c++/14/bits/regex.h:1317:5: 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>&)'
 1317 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1317:5: note:   template argument deduction/substitution failed:
a.cc:110:13: note:   'mint' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
  110 |   while(ans<0) ans+=MOD;
      |             ^
/usr/include/c++/14/bits/regex.h:1391:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const typename std::iterator_traits<_Iter>::value_type*, const sub_match<_BiIter>&)'
 1391 |     operator<(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1391:5: note:   template argument deduction/substitution failed:
a.cc:110:13: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
  110 |   while(ans<0) ans+=MOD;
      |             ^
/usr/include/c++/14/bits/regex.h:1485:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)'
 1485 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1485:5: note:   template argument deduction/substitution failed:
a.cc:110:13: note:   'mint' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
  110 |   while(ans<0) ans+=MOD;
      |             ^
/usr/include/c++/14/bits/regex.h:1560:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const typename std::iterator_traits<_Iter>::value_type&, const sub_match<_BiIter>&)'
 1560 |     operator<(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1560:5: note:   template argument deduction/substitution failed:
a.cc:110:13: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
  110 |   while(ans<0) ans+=MOD;
      |             ^
/usr/include/c++/14/bits/regex.h:1660:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)'
 1660 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1660:5: note:   template argument deduction/substitution failed:
a.cc:110:13: note:   'mint' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
  110 |   while(ans<0) ans+=MOD;
      |             ^
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:1045:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator<(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1045 |     operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1045:5: note:   template argument deduction/substitution failed:
a.cc:110:13: note:   'mint' is not derived from 'const std::pair<_T1, _T2>'
  110 |   while(ans<0) ans+=MOD;
      |             ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:448:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  448 |     operator<(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:448:5: note:   template argument deduction/substitution failed:
a.cc:110:13: note:   'mint' is not derived from 'const std::reverse_iterator<_Iterator>'
  110 |   while(ans<0) ans+=MOD;
      |             ^
/usr/include/c++/14/bits/stl_iterator.h:493:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  493 |     operator<(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note:   template argument deduction/substitution failed:
a.cc:110:13: note:   'mint' is not derived from 'const std::reverse_iterator<_Iterator>'
  110 |   while(ans<0) ans+=MOD;
      |             ^
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1694 |     operator<(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note:   template argument deduction/substitution failed:
a.cc:110:13: note:   'mint' is not derived from 'const std::move_iterator<_IteratorL>'
  110 |   while(ans<0) ans+=MOD;
      |             ^
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1760 |     operator<(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note:   template argument deduction/substitution failed:
a.cc:110:13: note:   'mint' is not derived from 'const std::move_iterator<_IteratorL>'
  110 |   while(ans<0) ans+=MOD;
      |             ^
In file included from /usr/include/c++/14/bits/basic_string.h:47,
                 from /usr/include/c++/14/string:54,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/usr/include/c++/14/string_view:673:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(basic_string_view<_CharT, _Traits>, basic_string_view<_CharT, _Traits>)'
  673 |     operator< (basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:673:5: note:   template argument deduction/substitution failed:
a.cc:110:13: note:   'mint' is not derived from 'std::basic_string_view<_CharT, _Traits>'
  110 |   while(ans<0) ans+=MOD;
      |             ^
/usr/include/c++/14/string_view:680:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(basic_string_view<_CharT, _Traits>, __type_identity_t<basic_string_view<_CharT, _Traits> >)'
  680 |     operator< (basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:680:5: note:   template argument deduction/substitution failed:
a.cc:110:13: note:   'mint' is not derived from 'std::basic_string_view<_CharT, _Traits>'
  110 |   while(ans<0) ans+=MOD;
      |             ^
/usr/include/c++/14/string_view:688:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(__type_identity_t<basic_string_view<_CharT, _Traits> >, basic_string_view<_CharT, _Traits>)'
  688 |     operator< (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:688:5: note:   template argument deduction/substitution failed:
a.cc:110:13: note:   mismatched types 'std::basic_string_view<_CharT, _Traits>' and 'int'
  110 |   while(ans<0) ans+=MOD;
      |             ^
/usr/include/c++/14/bits/basic_string.h:3874:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3874 |     operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3874:5: note:   template argument deduction/substitution failed:
a.cc:110:13: note:   'mint' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
  110 |   while(ans<0) ans+=MOD;
      |             ^
/usr/include/c++/14/bits/basic_string.h:3888:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const _CharT*)'
 3888 |     operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3888:5: note:   template argument deduction/substitution failed:
a.cc:110:13: note:   'mint' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
  110 |   while(ans<0) ans+=MOD;
      |             ^
/usr/include/c++/14/bits/basic_string.h:3901:5: note: candidate: 'template<c