Language: C++

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


bool isLunlun(string num, vector<bool> &vec){
    if(num.size()==1){
        vec.push_back(true);
        return true;
    }

    string tmp = num;
    int dif = (int)(num.at(0)-'0') - (int)(num.at(1)-'0');
    if(dif<=1 && dif>=-1){
        if(num/10==0){
            vec.push_back(true);
            return true;
        }
        num.erase(num.begin());
        if(vec.at(stoll(num)-1)){
            vec.push_back(true);
            return true;
        }
    }
    
    vec.push_back(false);
    return false;
}


int main(void){
    int k;
    cin >> k;

    long long i=1;
    long long ans=0;
    vector<bool> vec;   //答え格納用
    int count=0;
    while(1){
        if(isLunlun(to_string(i),vec)){
            ans = i; count++;
            //cout << ans << endl;
            if(count==k){
                cout << ans << endl;
                return 0;
            }
        }
        i++;
    }

}

Compiler output:
a.cc: In function 'bool isLunlun(std::string, std::vector<bool>&)':
a.cc:14:15: error: no match for 'operator/' (operand types are 'std::string' {aka 'std::__cxx11::basic_string<char>'} and 'int')
   14 |         if(num/10==0){
      |            ~~~^~~
      |            |   |
      |            |   int
      |            std::string {aka std::__cxx11::basic_string<char>}
In file included from /usr/include/c++/14/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:127,
                 from a.cc:1:
/usr/include/c++/14/complex:430:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator/(const complex<_Tp>&, const complex<_Tp>&)'
  430 |     operator/(const complex<_Tp>& __x, const complex<_Tp>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:430:5: note:   template argument deduction/substitution failed:
a.cc:14:16: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::complex<_Tp>'
   14 |         if(num/10==0){
      |                ^~
/usr/include/c++/14/complex:439:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator/(const complex<_Tp>&, const _Tp&)'
  439 |     operator/(const complex<_Tp>& __x, const _Tp& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:439:5: note:   template argument deduction/substitution failed:
a.cc:14:16: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::complex<_Tp>'
   14 |         if(num/10==0){
      |                ^~
/usr/include/c++/14/complex:448:5: note: candidate: 'template<class _Tp> std::complex<_Tp> std::operator/(const _Tp&, const complex<_Tp>&)'
  448 |     operator/(const _Tp& __x, const complex<_Tp>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/complex:448:5: note:   template argument deduction/substitution failed:
a.cc:14:16: note:   mismatched types 'const std::complex<_Tp>' and 'int'
   14 |         if(num/10==0){
      |                ^~
In file included from /usr/include/c++/14/valarray:605,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:166:
/usr/include/c++/14/bits/valarray_after.h:408:5: note: candidate: 'template<class _Dom1, class _Dom2> std::_Expr<std::__detail::_BinClos<std::__divides, std::_Expr, std::_Expr, _Dom1, _Dom2>, typename std::__fun<std::__divides, typename _Dom1::value_type>::result_type> std::operator/(const _Expr<_Dom1, typename _Dom1::value_type>&, const _Expr<_Dom2, typename _Dom2::value_type>&)'
  408 |     _DEFINE_EXPR_BINARY_OPERATOR(/, struct std::__divides)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:408:5: note:   template argument deduction/substitution failed:
a.cc:14:16: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   14 |         if(num/10==0){
      |                ^~
/usr/include/c++/14/bits/valarray_after.h:408:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__divides, std::_Expr, std::_Constant, _Dom, typename _Dom::value_type>, typename std::__fun<std::__divides, typename _Dom1::value_type>::result_type> std::operator/(const _Expr<_Dom1, typename _Dom1::value_type>&, const typename _Dom::value_type&)'
  408 |     _DEFINE_EXPR_BINARY_OPERATOR(/, struct std::__divides)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:408:5: note:   template argument deduction/substitution failed:
a.cc:14:16: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   14 |         if(num/10==0){
      |                ^~
/usr/include/c++/14/bits/valarray_after.h:408:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__divides, std::_Constant, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__divides, typename _Dom1::value_type>::result_type> std::operator/(const typename _Dom::value_type&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  408 |     _DEFINE_EXPR_BINARY_OPERATOR(/, struct std::__divides)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:408:5: note:   template argument deduction/substitution failed:
a.cc:14:16: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'int'
   14 |         if(num/10==0){
      |                ^~
/usr/include/c++/14/bits/valarray_after.h:408:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__divides, std::_Expr, std::_ValArray, _Dom, typename _Dom::value_type>, typename std::__fun<std::__divides, typename _Dom1::value_type>::result_type> std::operator/(const _Expr<_Dom1, typename _Dom1::value_type>&, const valarray<typename _Dom::value_type>&)'
  408 |     _DEFINE_EXPR_BINARY_OPERATOR(/, struct std::__divides)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:408:5: note:   template argument deduction/substitution failed:
a.cc:14:16: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::_Expr<_Dom1, typename _Dom1::value_type>'
   14 |         if(num/10==0){
      |                ^~
/usr/include/c++/14/bits/valarray_after.h:408:5: note: candidate: 'template<class _Dom> std::_Expr<std::__detail::_BinClos<std::__divides, std::_ValArray, std::_Expr, typename _Dom::value_type, _Dom>, typename std::__fun<std::__divides, typename _Dom1::value_type>::result_type> std::operator/(const valarray<typename _Dom::value_type>&, const _Expr<_Dom1, typename _Dom1::value_type>&)'
  408 |     _DEFINE_EXPR_BINARY_OPERATOR(/, struct std::__divides)
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/valarray_after.h:408:5: note:   template argument deduction/substitution failed:
a.cc:14:16: note:   mismatched types 'const std::_Expr<_Dom1, typename _Dom1::value_type>' and 'int'
   14 |         if(num/10==0){
      |                ^~
/usr/include/c++/14/valarray:1199:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__divides, std::_ValArray, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__divides, _Tp>::result_type> std::operator/(const valarray<_Tp>&, const valarray<_Tp>&)'
 1199 | _DEFINE_BINARY_OPERATOR(/, __divides)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1199:1: note:   template argument deduction/substitution failed:
a.cc:14:16: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::valarray<_Tp>'
   14 |         if(num/10==0){
      |                ^~
/usr/include/c++/14/valarray:1199:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__divides, std::_ValArray, std::_Constant, _Tp, _Tp>, typename std::__fun<std::__divides, _Tp>::result_type> std::operator/(const valarray<_Tp>&, const typename valarray<_Tp>::value_type&)'
 1199 | _DEFINE_BINARY_OPERATOR(/, __divides)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1199:1: note:   template argument deduction/substitution failed:
a.cc:14:16: note:   'std::string' {aka 'std::__cxx11::basic_string<char>'} is not derived from 'const std::valarray<_Tp>'
   14 |         if(num/10==0){
      |                ^~
/usr/include/c++/14/valarray:1199:1: note: candidate: 'template<class _Tp> std::_Expr<std::__detail::_BinClos<std::__divides, std::_Constant, std::_ValArray, _Tp, _Tp>, typename std::__fun<std::__divides, _Tp>::result_type> std::operator/(const typename valarray<_Tp>::value_type&, const valarray<_Tp>&)'
 1199 | _DEFINE_BINARY_OPERATOR(/, __divides)
      | ^~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/valarray:1199:1: note:   template argument deduction/substitution failed:
a.cc:14:16: note:   mismatched types 'const std::valarray<_Tp>' and 'int'
   14 |         if(num/10==0){
      |                ^~