Language: C++

#include "bits/stdc++.h"
using namespace std;
#define Would
#define you
const long long INF = 99999999999999999;
const long long MOD = 1e9 + 7;
const double pi = 3.1415926535897932384626;
const int SIZE = 1 << 17;

int main() {
	string h;
	cin >> h;
	vector<char>ans;
	for (int i = 0; i < h.length(); ++i) {
		if (h[i] == '0') { ans.push_back("0"); }
		else if (h[i] == '1') { ans.push_back("1"); }
		else if (v.size() != 0) { ans.pop_back(); }
	}
	for (int i = 0; i < v.size(); ++i) { cout << v[i]; }
	cout << endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:15:49: error: no matching function for call to 'push_back(const char [2])'
   15 |                 if (h[i] == '0') { ans.push_back("0"); }
      |                                    ~~~~~~~~~~~~~^~~~~
In file included from /usr/include/c++/14/vector:66,
                 from /usr/include/c++/14/functional:64,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_vector.h:1283:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(const value_type&) [with _Tp = char; _Alloc = std::allocator<char>; value_type = char]' (near match)
 1283 |       push_back(const value_type& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1283:7: note:   conversion of argument 1 would be ill-formed:
a.cc:15:50: error: invalid conversion from 'const char*' to 'std::vector<char>::value_type' {aka 'char'} [-fpermissive]
   15 |                 if (h[i] == '0') { ans.push_back("0"); }
      |                                                  ^~~
      |                                                  |
      |                                                  const char*
/usr/include/c++/14/bits/stl_vector.h:1300:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(value_type&&) [with _Tp = char; _Alloc = std::allocator<char>; value_type = char]' (near match)
 1300 |       push_back(value_type&& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1300:7: note:   conversion of argument 1 would be ill-formed:
a.cc:15:50: error: invalid conversion from 'const char*' to 'std::vector<char>::value_type' {aka 'char'} [-fpermissive]
   15 |                 if (h[i] == '0') { ans.push_back("0"); }
      |                                                  ^~~
      |                                                  |
      |                                                  const char*
a.cc:16:54: error: no matching function for call to 'push_back(const char [2])'
   16 |                 else if (h[i] == '1') { ans.push_back("1"); }
      |                                         ~~~~~~~~~~~~~^~~~~
/usr/include/c++/14/bits/stl_vector.h:1283:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(const value_type&) [with _Tp = char; _Alloc = std::allocator<char>; value_type = char]' (near match)
 1283 |       push_back(const value_type& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1283:7: note:   conversion of argument 1 would be ill-formed:
a.cc:16:55: error: invalid conversion from 'const char*' to 'std::vector<char>::value_type' {aka 'char'} [-fpermissive]
   16 |                 else if (h[i] == '1') { ans.push_back("1"); }
      |                                                       ^~~
      |                                                       |
      |                                                       const char*
/usr/include/c++/14/bits/stl_vector.h:1300:7: note: candidate: 'void std::vector<_Tp, _Alloc>::push_back(value_type&&) [with _Tp = char; _Alloc = std::allocator<char>; value_type = char]' (near match)
 1300 |       push_back(value_type&& __x)
      |       ^~~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:1300:7: note:   conversion of argument 1 would be ill-formed:
a.cc:16:55: error: invalid conversion from 'const char*' to 'std::vector<char>::value_type' {aka 'char'} [-fpermissive]
   16 |                 else if (h[i] == '1') { ans.push_back("1"); }
      |                                                       ^~~
      |                                                       |
      |                                                       const char*
a.cc:17:26: error: 'v' was not declared in this scope
   17 |                 else if (v.size() != 0) { ans.pop_back(); }
      |                          ^
a.cc:19:29: error: 'v' was not declared in this scope
   19 |         for (int i = 0; i < v.size(); ++i) { cout << v[i]; }
      |                             ^