Language: C++

#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)
using namespace std;
using ll = long long;

//テストケースはあんまり見ないほうが良い。デバッグする能力が必要.
int main()
{
    string s;
    cin >> s; 
    string a[] = {'R','U', 'D'};
    string b[] = {'L', 'U', 'D'};
    int ans =0;
    rep(i,n){
        if(i%2==0){
            rep(j,3){
                if(a[j] == s[i])++ans;
            }
        }else{
            rep(j,3){
                if(b[j] == s[i])++ans;
            }
        }
    }
    if(ans == s.size())cout <<"Yes" <<endl;
    else cout << "No" << endl;
    return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:11:19: error: conversion from 'char' to non-scalar type 'std::string' {aka 'std::__cxx11::basic_string<char>'} requested
   11 |     string a[] = {'R','U', 'D'};
      |                   ^~~
a.cc:11:23: error: conversion from 'char' to non-scalar type 'std::string' {aka 'std::__cxx11::basic_string<char>'} requested
   11 |     string a[] = {'R','U', 'D'};
      |                       ^~~
a.cc:11:28: error: conversion from 'char' to non-scalar type 'std::string' {aka 'std::__cxx11::basic_string<char>'} requested
   11 |     string a[] = {'R','U', 'D'};
      |                            ^~~
a.cc:12:19: error: conversion from 'char' to non-scalar type 'std::string' {aka 'std::__cxx11::basic_string<char>'} requested
   12 |     string b[] = {'L', 'U', 'D'};
      |                   ^~~
a.cc:12:24: error: conversion from 'char' to non-scalar type 'std::string' {aka 'std::__cxx11::basic_string<char>'} requested
   12 |     string b[] = {'L', 'U', 'D'};
      |                        ^~~
a.cc:12:29: error: conversion from 'char' to non-scalar type 'std::string' {aka 'std::__cxx11::basic_string<char>'} requested
   12 |     string b[] = {'L', 'U', 'D'};
      |                             ^~~
a.cc:14:11: error: 'n' was not declared in this scope
   14 |     rep(i,n){
      |           ^
a.cc:2:40: note: in definition of macro 'rep'
    2 | #define rep(i, n) for (int i = 0; i < (n); ++i)
      |                                        ^
a.cc:17:25: error: no match for 'operator==' (operand types are 'std::string' {aka 'std::__cxx11::basic_string<char>'} and '__gnu_cxx::__alloc_traits<std::allocator<char>, char>::value_type' {aka 'char'})
   17 |                 if(a[j] == s[i])++ans;
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:17:31: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   17 |                 if(a[j] == s[i])++ans;
      |                               ^
/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:17:31: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and '__gnu_cxx::__alloc_traits<std::allocator<char>, char>::value_type' {aka 'char'}
   17 |                 if(a[j] == s[i])++ans;
      |                               ^
/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:17:31: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   17 |                 if(a[j] == s[i])++ans;
      |                               ^
/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:17:31: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and '__gnu_cxx::__alloc_traits<std::allocator<char>, char>::value_type' {aka 'char'}
   17 |                 if(a[j] == s[i])++ans;
      |                               ^
/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:17:31: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   17 |                 if(a[j] == s[i])++ans;
      |                               ^
/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:17:31: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and '__gnu_cxx::__alloc_traits<std::allocator<char>, char>::value_type' {aka 'char'}
   17 |                 if(a[j] == s[i])++ans;
      |                               ^
/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:17:31: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   17 |                 if(a[j] == s[i])++ans;
      |                               ^
/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:17:31: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::__cxx11::match_results<_BiIter, _Alloc>'
   17 |                 if(a[j] == s[i])++ans;
      |                               ^
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:17:31: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::pair<_T1, _T2>'
   17 |                 if(a[j] == s[i])++ans;
      |                               ^
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:17:31: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::reverse_iterator<_Iterator>'
   17 |                 if(a[j] == s[i])++ans;
      |                               ^
/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:17:31: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::reverse_iterator<_Iterator>'
   17 |                 if(a[j] == s[i])++ans;
      |                               ^
/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:17:31: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::move_iterator<_IteratorL>'
   17 |                 if(a[j] == s[i])++ans;
      |                               ^
/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:17:31: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::move_iterator<_IteratorL>'
   17 |                 if(a[j] == s[i])++ans;
      |