Language: C++

#include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;

int main(int argc, char *argv[]){
  int n;
  while(cin >> n, n){
    string s[1001];
    for (int i = 0; i < n; i++) {
      cin >> s[i];
    }
    int depth = 0;
    for (int i = 1; i < n; i++) {
      depth = max(depth, s[i]);
      for (int j = 0; j < s[i].length(); j++) {
        if(s[i][j] != '.')break;
        if(s[i][j + 1] != '.'){
          s[i][j] = '+';
        }else{
          s[i][j] = ' ';
        }
      }
    }
    for (int i = 0; i <= depth; i++) {
      int count = 0;
      for (int j = 0; j < n && i < s[j].length(); j++) {
        if(s[j][i] == '+'){
          for (int k = 1; k <= count &&
                 s[j - count - 1][i] == '+'; k++) {
            s[j - k][i] = '|';
          }
        }
        if(s[j][i] == ' '){
          count++;
        }else{
          count = 0;
        }
      }
    }
    for (int i = 0; i < n; i++) {
      std::cout << s[i] << std::endl;
    }
  }
  return 0;
}

Compiler output:
a.cc: In function 'int main(int, char**)':
a.cc:15:18: error: no matching function for call to 'max(int&, std::string&)'
   15 |       depth = max(depth, s[i]);
      |               ~~~^~~~~~~~~~~~~
In file included from /usr/include/c++/14/string:51,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_algobase.h:257:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)'
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
a.cc:15:18: note:   deduced conflicting types for parameter 'const _Tp' ('int' and 'std::string' {aka 'std::__cxx11::basic_string<char>'})
   15 |       depth = max(depth, s[i]);
      |               ~~~^~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)'
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/algorithm:61,
                 from a.cc:3:
/usr/include/c++/14/bits/stl_algo.h:5706:5: note: candidate: 'template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)'
 5706 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5706:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5716:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)'
 5716 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5716:5: note:   template argument deduction/substitution failed:
a.cc:15:18: note:   mismatched types 'std::initializer_list<_Tp>' and 'int'
   15 |       depth = max(depth, s[i]);
      |               ~~~^~~~~~~~~~~~~