Language: C++

#include <algorithm>
#include <bitset>
#include <tuple>
#include <cstdint>
#include <cstdio>
#include <cctype>
#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
#include <cassert>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <ctime>
#include <deque>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <limits>
#include <map>
#include <memory>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
#define ArraySizeOf(array)     (sizeof(array) / sizeof(array[0]))
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define REP(i,n) for(int i=1;i<n;i++)
#define int long long
#define rev(i,n) for(int i=n-1;i>=0;i--)
#define _GLIBCXX_DEBUG
int INF = 1e9+7;
unsigned NthDayOfWeekToDay(unsigned n, unsigned dow, unsigned dow1)
{
unsigned day;
if(dow < dow1) dow += 7;
day = dow - dow1;
day += 7 * n - 6;
return day;
}
unsigned DayToWeekNumber(unsigned day)
{
  return (day - 1) / 7 + 1;
}
unsigned AnotherDayOfWeek(unsigned day, unsigned day0, unsigned dow0)
{
  return (dow0 + 35 + day - day0) % 7;
}
using namespace std;
signed main(){
  string S;
  cin>>S;
  rep(i,S.size()){
    if(S.at(i)=='?'){
      if(S.at(i+1)=='D')S.at(i)="P";
      else S.at(i)="D";
    }
  }
  cout<<S<endl;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:64:33: error: invalid conversion from 'const char*' to '__gnu_cxx::__alloc_traits<std::allocator<char>, char>::value_type' {aka 'char'} [-fpermissive]
   64 |       if(S.at(i+1)=='D')S.at(i)="P";
      |                                 ^~~
      |                                 |
      |                                 const char*
a.cc:65:20: error: invalid conversion from 'const char*' to '__gnu_cxx::__alloc_traits<std::allocator<char>, char>::value_type' {aka 'char'} [-fpermissive]
   65 |       else S.at(i)="D";
      |                    ^~~
      |                    |
      |                    const char*
a.cc:68:10: error: no match for 'operator<' (operand types are 'std::basic_ostream<char>' and '<unresolved overloaded function type>')
   68 |   cout<<S<endl;
      |   ~~~~~~~^~~~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/algorithm:60,
                 from a.cc:1:
/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:68:11: note:   'std::basic_ostream<char>' is not derived from 'const std::pair<_T1, _T2>'
   68 |   cout<<S<endl;
      |           ^~~~
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:68:11: note:   'std::basic_ostream<char>' is not derived from 'const std::reverse_iterator<_Iterator>'
   68 |   cout<<S<endl;
      |           ^~~~
/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:68:11: note:   'std::basic_ostream<char>' is not derived from 'const std::reverse_iterator<_Iterator>'
   68 |   cout<<S<endl;
      |           ^~~~
/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:68:11: note:   'std::basic_ostream<char>' is not derived from 'const std::move_iterator<_IteratorL>'
   68 |   cout<<S<endl;
      |           ^~~~
/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:68:11: note:   'std::basic_ostream<char>' is not derived from 'const std::move_iterator<_IteratorL>'
   68 |   cout<<S<endl;
      |           ^~~~
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 a.cc:2:
/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:68:11: note:   'std::basic_ostream<char>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   68 |   cout<<S<endl;
      |           ^~~~
/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:68:11: note:   'std::basic_ostream<char>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   68 |   cout<<S<endl;
      |           ^~~~
/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:68:11: note:   couldn't deduce template parameter '_CharT'
   68 |   cout<<S<endl;
      |           ^~~~
/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:68:11: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   68 |   cout<<S<endl;
      |           ^~~~
/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:68:11: note:   'std::basic_ostream<char>' is not derived from 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>'
   68 |   cout<<S<endl;
      |           ^~~~
/usr/include/c++/14/bits/basic_string.h:3901:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const _CharT*, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3901 |     operator<(const _CharT* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3901:5: note:   template argument deduction/substitution failed:
a.cc:68:11: note:   mismatched types 'const _CharT*' and 'std::basic_ostream<char>'
   68 |   cout<<S<endl;
      |           ^~~~
In file included from /usr/include/c++/14/bits/memory_resource.h:47,
                 from /usr/include/c++/14/string:68:
/usr/include/c++/14/tuple:2600:5: note: candidate: 'template<class ... _TElements, class ... _UElements> constexpr bool std::operator<(const tuple<_UTypes ...>&, const tuple<_Elements ...>&)'
 2600 |     operator<(const tuple<_TElements...>& __t,
      |     ^~~~~~~~
/usr/include/c++/14/tuple:2600:5: note:   template argument deduction/substitution failed:
a.cc:68:11: note:   'std::basic_ostream<char>' is not derived from 'const std::tuple<_UTypes ...>'
   68 |   cout<<S<endl;
      |           ^~~~
In file included from /usr/include/c++/14/deque:66,
                 from a.cc:16:
/usr/include/c++/14/bits/stl_deque.h:2334:5: note: candidate: 'template<class _Tp, class _Alloc> bool std::operator<(const deque<_Tp, _Alloc>&, const deque<_Tp, _Alloc>&)'
 2334 |     operator<(const deque<_Tp, _Alloc>& __x, const deque<_Tp, _Alloc>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_deque.h:2334:5: note:   template argument deduction/substitution failed:
a.cc:68:11: note:   'std::basic_ostream<char>' is not derived from 'const std::deque<_Tp, _Alloc>'
   68 |   cout<<S<endl;
      |           ^~~~
In file included from /usr/include/c++/14/vector:66,
                 from /usr/include/c++/14/functional:64,
                 from a.cc:18:
/usr/include/c++/14/bits/stl_vector.h:2089:5: note: candidate: 'template<class _Tp, class _Alloc> bool std::operator<(const vector<_Tp, _Alloc>&, const vector<_Tp, _Alloc>&)'
 2089 |     operator<(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_vector.h:2089:5: note:   template argument deduction/substitution failed:
a.cc:68:11: note:   'std::basic_ostream<char>' is not derived from 'const std::vector<_Tp, _Alloc>'
   68 |   cout<<S<endl;
      |           ^~~~
In file included from /usr/include/c++/14/functional:65:
/usr/include/c++/14/array:339:5: note: candidate: 'template<class _Tp, long unsigned int _Nm> bool std::operator<(const array<_Tp, _Nm>&, const array<_Tp, _Nm>&)'
  339 |     operator<(const array<_Tp, _Nm>& __a, const array<_Tp, _Nm>& __b)
      |     ^~~~~~~~
/usr/include/c++/14/array:339:5: note:   template argument deduction/substitution failed:
a.cc:68:11: note:   'std::basic_ostream<char>' is not derived from 'const std::array<_Tp, _Nm>'
   68 |   cout<<S<endl;
      |           ^~~~
In file included from /usr/include/c++/14/list:65,
                 from a.cc:22:
/usr/include/c++/14/bits/stl_list.h:2188:5: note: candidate: 'template<class _Tp, class _Alloc> bool std::operator<(const __cxx11::list<_Tp, _Alloc>&, const __cxx11::list<_Tp, _Alloc>&)'
 2188 |     operator<(const list<_Tp, _Alloc>& __x, const list<_Tp, _Alloc>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_list.h:2188:5: note:   template argument deduction/substitution failed:
a.cc:68:11: