#include <iostream>
#define int long long int
using namespace std;

int n, m, r, Cnt, RSx[2] = {0, 1}, RSy[2] = {0, 1}, i, j, k; char a[103][103];

void Dfs (int x, int y, int i, int j) {
    if (j > r) {
        Cnt++; return;
    } if (a[x][y] == '.' or x < 0 or x >= n or y < 0 or y >= m) {
        return;
    }
    
    Dfs(x + RSx[i], y + RSy[i], i, j + 1);
    return;
}

signed main () {
    ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
    
    cin >> n >> m >> r;
    for (i = 0; i < n; ++i) {
        cin >> a[i];
    } for (i = 0; i < n; ++i) {
        for (j = 0; j < m; ++j) {
            if (a[i][j] == '.') {
                for (k = 0; k < 2; ++k) {
                    Dfs(i, j, k, 1);
                }
            }
        }
    }
    
    cout << r == 1 ? Cnt / 2 : Cnt;
    return 0;
}

Code有以下Error,

main.cpp: In function ‘int main()’:
main.cpp:35:15: error: no match for ‘operator==’ (operand types are ‘std::basic_ostream::__ostream_type’ {aka ‘std::basic_ostream’} and ‘int’)
   35 |     cout << r == 1 ? Cnt / 2 : Cnt;
      |     ~~~~~~~~~ ^~ ~
      |          |       |
      |          |       int
      |          std::basic_ostream<char>::__ostream_type {aka std::basic_ostream<char>}
In file included from /usr/include/c++/11/bits/stl_algobase.h:67,
                 from /usr/include/c++/11/bits/char_traits.h:39,
                 from /usr/include/c++/11/ios:40,
                 from /usr/include/c++/11/ostream:38,
                 from /usr/include/c++/11/iostream:39,
                 from main.cpp:1:
/usr/include/c++/11/bits/stl_iterator.h:494:5: note: candidate: ‘template constexpr bool std::operator==(const std::reverse_iterator<_IteratorL>&, const std::reverse_iterator<_IteratorR>&) requires requires{{std::operator==::__x->base() == std::operator==::__y->base()} -> decltype(auto) [requires std::convertible_to<, bool>];}’ (reversed)
  494 |     operator==(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/11/bits/stl_iterator.h:494:5: note:   template argument deduction/substitution failed:
main.cpp:35:18: note:   mismatched types ‘const std::reverse_iterator<_IteratorL>’ and ‘int’
   35 |     cout << r == 1 ? Cnt / 2 : Cnt;
      |                  ^
In file included from /usr/include/c++/11/bits/stl_algobase.h:67,
                 from /usr/include/c++/11/bits/char_traits.h:39,
                 from /usr/include/c++/11/ios:40,
                 from /usr/include/c++/11/ostream:38,
                 from /usr/include/c++/11/iostream:39,
                 from main.cpp:1:
/usr/include/c++/11/bits/stl_iterator.h:1533:5: note: candidate: ‘template constexpr bool std::operator==(const std::move_iterator<_IteratorL>&, const std::move_iterator<_IteratorR>&) requires requires{{std::operator==::__x->base() == std::operator==::__y->base()} -> decltype(auto) [requires std::convertible_to<, bool>];}’ (reversed)
 1533 |     operator==(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/11/bits/stl_iterator.h:1533:5: note:   template argument deduction/substitution failed:
main.cpp:35:18: note:   mismatched types ‘const std::move_iterator<_IteratorL>’ and ‘int’
   35 |     cout << r == 1 ? Cnt / 2 : Cnt;
      |                  ^
In file included from /usr/include/c++/11/string:41,
                 from /usr/include/c++/11/bits/locale_classes.h:40,
                 from /usr/include/c++/11/bits/ios_base.h:41,
                 from /usr/include/c++/11/ios:42,
                 from /usr/include/c++/11/ostream:38,
                 from /usr/include/c++/11/iostream:39,
                 from main.cpp:1:
/usr/include/c++/11/bits/allocator.h:218:5: note: candidate: ‘template constexpr bool std::operator==(const std::allocator<_CharT>&, const std::allocator<_T2>&)’ (reversed)
  218 |     operator==(const allocator<_T1>&, const allocator<_T2>&)
      |     ^~~~~~~~
/usr/include/c++/11/bits/allocator.h:218:5: note:   template argument deduction/substitution failed:
main.cpp:35:18: note:   mismatched types ‘const std::allocator<_CharT>’ and ‘int’
   35 |     cout << r == 1 ? Cnt / 2 : Cnt;
      |                  ^
In file included from /usr/include/c++/11/bits/basic_string.h:48,
                 from /usr/include/c++/11/string:55,
                 from /usr/include/c++/11/bits/locale_classes.h:40,
                 from /usr/include/c++/11/bits/ios_base.h:41,
                 from /usr/include/c++/11/ios:42,
                 from /usr/include/c++/11/ostream:38,
                 from /usr/include/c++/11/iostream:39,
                 from main.cpp:1:
/usr/include/c++/11/string_view:541:5: note: candidate: ‘template constexpr bool std::operator==(std::basic_string_view<_CharT, _Traits>, std::__type_identity_t >)’ (reversed)
  541 |     operator==(basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/11/string_view:541:5: note:   template argument deduction/substitution failed:
main.cpp:35:18: note:   mismatched types ‘std::basic_string_view<_CharT, _Traits>’ and ‘int’
   35 |     cout << r == 1 ? Cnt / 2 : Cnt;
      |                  ^
In file included from /usr/include/c++/11/string:55,
                 from /usr/include/c++/11/bits/locale_classes.h:40,
                 from /usr/include/c++/11/bits/ios_base.h:41,
                 from /usr/include/c++/11/ios:42,
                 from /usr/include/c++/11/ostream:38,
                 from /usr/include/c++/11/iostream:39,
                 from main.cpp:1:
/usr/include/c++/11/bits/basic_string.h:6248:5: note: candidate: ‘template bool std::operator==(const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>&, const _CharT*)’ (reversed)
 6248 |     operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/11/bits/basic_string.h:6248:5: note:   template argument deduction/substitution failed:
main.cpp:35:18: note:   mismatched types ‘const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>’ and ‘int’
   35 |     cout << r == 1 ? Cnt / 2 : Cnt;
      |                  ^
In file included from /usr/include/c++/11/bits/ios_base.h:46,
                 from /usr/include/c++/11/ios:42,
                 from /usr/include/c++/11/ostream:38,
                 from /usr/include/c++/11/iostream:39,
                 from main.cpp:1:
/usr/include/c++/11/system_error:368:3: note: candidate: ‘bool std::operator==(const std::error_code&, const std::error_condition&)’ (reversed)
  368 |   operator==(const error_code& __lhs, const error_condition& __rhs) noexcept
      |   ^~~~~~~~
/usr/include/c++/11/system_error:368:32: note:   no known conversion for argument 1 from ‘int’ to ‘const std::error_code&’
  368 |   operator==(const error_code& __lhs, const error_condition& __rhs) noexcept
      |              ~~~~~~~~~~~~~~~~~~^~~~~
main.cpp:35:15: note: candidate: ‘operator==(int, int)’ (built-in)
   35 |     cout << r == 1 ? Cnt / 2 : Cnt;
      |     ~~~~~~~~~~^~~~
main.cpp:35:15: note:   no known conversion for argument 1 from ‘std::basic_ostream::__ostream_type’ {aka ‘std::basic_ostream’} to ‘int’
In file included from /usr/include/c++/11/iosfwd:40,
                 from /usr/include/c++/11/ios:38,
                 from /usr/include/c++/11/ostream:38,
                 from /usr/include/c++/11/iostream:39,
                 from main.cpp:1:
/usr/include/c++/11/bits/postypes.h:222:5: note: candidate: ‘template bool std::operator==(const std::fpos<_StateT>&, const std::fpos<_StateT>&)’
  222 |     operator==(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/11/bits/postypes.h:222:5: note:   template argument deduction/substitution failed:
main.cpp:35:18: note:   ‘std::basic_ostream::__ostream_type’ {aka ‘std::basic_ostream’} is not derived from ‘const std::fpos<_StateT>’
   35 |     cout << r == 1 ? Cnt / 2 : Cnt;
      |                  ^
In file included from /usr/include/c++/11/bits/stl_algobase.h:64,
                 from /usr/include/c++/11/bits/char_traits.h:39,
                 from /usr/include/c++/11/ios:40,
                 from /usr/include/c++/11/ostream:38,
                 from /usr/include/c++/11/iostream:39,
                 from main.cpp:1:
/usr/include/c++/11/bits/stl_pair.h:466:5: note: candidate: ‘template constexpr bool std::operator==(const std::pair<_T1, _T2>&, const std::pair<_T1, _T2>&)’
  466 |     operator==(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/11/bits/stl_pair.h:466:5: note:   template argument deduction/substitution failed:
main.cpp:35:18: note:   ‘std::basic_ostream::__ostream_type’ {aka ‘std::basic_ostream’} is not derived from ‘const std::pair<_T1, _T2>’
   35 |     cout << r == 1 ? Cnt / 2 : Cnt;
      |                  ^
In file included from /usr/include/c++/11/bits/basic_string.h:48,
                 from /usr/include/c++/11/string:55,
                 from /usr/include/c++/11/bits/locale_classes.h:40,
                 from /usr/include/c++/11/bits/ios_base.h:41,
                 from /usr/include/c++/11/ios:42,
                 from /usr/include/c++/11/ostream:38,
                 from /usr/include/c++/11/iostream:39,
                 from main.cpp:1:
/usr/include/c++/11/string_view:535:5: note: candidate: ‘template constexpr bool std::operator==(std::basic_string_view<_CharT, _Traits>, std::basic_string_view<_CharT, _Traits>)’
  535 |     operator==(basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/11/string_view:535:5: note:   template argument deduction/substitution failed:
main.cpp:35:18: note:   ‘std::basic_ostream’ is not derived from ‘std::basic_string_view<_CharT, _Traits>’
   35 |     cout << r == 1 ? Cnt / 2 : Cnt;
      |                  ^
In file included from /usr/include/c++/11/string:55,
                 from /usr/include/c++/11/bits/locale_classes.h:40,
                 from /usr/include/c++/11/bits/ios_base.h:41,
                 from /usr/include/c++/11/ios:42,
                 from /usr/include/c++/11/ostream:38,
                 from /usr/include/c++/11/iostream:39,
                 from main.cpp:1:
/usr/include/c++/11/bits/basic_string.h:6226:5: note: candidate: ‘template bool std::operator==(const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>&, const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>&)’
 6226 |     operator==(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/11/bits/basic_string.h:6226:5: note:   template argument deduction/substitution failed:
main.cpp:35:18: note:   ‘std::basic_ostream::__ostream_type’ {aka ‘std::basic_ostream’} is not derived from ‘const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>’
   35 |     cout << r == 1 ? Cnt / 2 : Cnt;
      |                  ^
In file included from /usr/include/c++/11/string:55,
                 from /usr/include/c++/11/bits/locale_classes.h:40,
                 from /usr/include/c++/11/bits/ios_base.h:41,
                 from /usr/include/c++/11/ios:42,
                 from /usr/include/c++/11/ostream:38,
                 from /usr/include/c++/11/iostream:39,
                 from main.cpp:1:
/usr/include/c++/11/bits/basic_string.h:6234:5: note: candidate: ‘template typename __gnu_cxx::__enable_if::__value, bool>::__type std::operator==(const std::__cxx11::basic_string<_CharT>&, const std::__cxx11::basic_string<_CharT>&)’
 6234 |     operator==(const basic_string<_CharT>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/11/bits/basic_string.h:6234:5: note:   template argument deduction/substitution failed:
main.cpp:35:18: note:   ‘std::basic_ostream::__ostream_type’ {aka ‘std::basic_ostream’} is not derived from ‘const std::__cxx11::basic_string<_CharT>’
   35 |     cout << r == 1 ? Cnt / 2 : Cnt;
      |                  ^
In file included from /usr/include/c++/11/bits/locale_facets.h:48,
                 from /usr/include/c++/11/bits/basic_ios.h:37,
                 from /usr/include/c++/11/ios:44,
                 from /usr/include/c++/11/ostream:38,
                 from /usr/include/c++/11/iostream:39,
                 from main.cpp:1:
/usr/include/c++/11/bits/streambuf_iterator.h:226:5: note: candidate: ‘template bool std::operator==(const std::istreambuf_iterator<_CharT, _Traits>&, const std::istreambuf_iterator<_CharT, _Traits>&)’
  226 |     operator==(const istreambuf_iterator<_CharT, _Traits>& __a,
      |     ^~~~~~~~
/usr/include/c++/11/bits/streambuf_iterator.h:226:5: note:   template argument deduction/substitution failed:
main.cpp:35:18: note:   ‘std::basic_ostream::__ostream_type’ {aka ‘std::basic_ostream’} is not derived from ‘const std::istreambuf_iterator<_CharT, _Traits>’
   35 |     cout << r == 1 ? Cnt / 2 : Cnt;
      |                  ^
In file included from /usr/include/c++/11/bits/ios_base.h:46,
                 from /usr/include/c++/11/ios:42,
                 from /usr/include/c++/11/ostream:38,
                 from /usr/include/c++/11/iostream:39,
                 from main.cpp:1:
/usr/include/c++/11/system_error:362:3: note: candidate: ‘bool std::operator==(const std::error_code&, const std::error_code&)’
  362 |   operator==(const error_code& __lhs, const error_code& __rhs) noexcept
      |   ^~~~~~~~
/usr/include/c++/11/system_error:362:32: note:   no known conversion for argument 1 from ‘std::basic_ostream::__ostream_type’ {aka ‘std::basic_ostream’} to ‘const std::error_code&’
  362 |   operator==(const error_code& __lhs, const error_code& __rhs) noexcept
      |              ~~~~~~~~~~~~~~~~~~^~~~~
/usr/include/c++/11/system_error:376:3: note: candidate: ‘bool std::operator==(const std::error_condition&, const std::error_condition&)’
  376 |   operator==(const error_condition& __lhs,
      |   ^~~~~~~~
/usr/include/c++/11/system_error:376:37: note:   no known conversion for argument 1 from ‘std::basic_ostream::__ostream_type’ {aka ‘std::basic_ostream’} to ‘const std::error_condition&’
  376 |   operator==(const error_condition& __lhs,
      |              ~~~~~~~~~~~~~~~~~~~~~~~^~~~~

谢谢,QaQ.