Language: C++

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

int main() {
  int H, W;
  cin >> H >> W;
  
  vector<vector<char>> table(H, vector<char>(W));
  vector<int> del_line();
  vector<int> del_row();
  
  for (int h = 0; h < H; h++) {
    for(int w = 0; w < W; w++) {
      cin >> table.at(h).at(w);
    }
  }
  
  for (int h = 0; h < H; h++) {
    bool flag = false;
    for(int w = 0; w < W; w++) {
      if(table.at(h).at(w) == '#'){
        flag = true;
        break;
      }
    }
    if(flag == false) del_line.push_back(h);
  }
  
  for (int w = 0; w < W; w++) {
    bool flag = false;
    for(int h = 0; h < H; h++) {
      if(table.at(h).at(w) == '#'){
        flag = true;
        break;
      }
    }
    if(flag == false) del_row.push_back(w);
  }
  
  for (int h = 0; h < H; h++) {
    bool flag = false;
    for (int i : del_line) {
      if (h == i) {
        flag = true;
        break;
      }
    }
    if(flag == true) break;
    
    for(int w = 0; w < W; w++) {
      for (int j : del_row) {
        if (w == j) {
          flag = true;
          break;
        }
      }
      if (flag == true) break;
      cout << table.at(h).at(w);
    }
    cout << endl;
  }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:9:23: warning: empty parentheses were disambiguated as a function declaration [-Wvexing-parse]
    9 |   vector<int> del_line();
      |                       ^~
a.cc:9:23: note: remove parentheses to default-initialize a variable
    9 |   vector<int> del_line();
      |                       ^~
      |                       --
a.cc:10:22: warning: empty parentheses were disambiguated as a function declaration [-Wvexing-parse]
   10 |   vector<int> del_row();
      |                      ^~
a.cc:10:22: note: remove parentheses to default-initialize a variable
   10 |   vector<int> del_row();
      |                      ^~
      |                      --
a.cc:26:32: error: request for member 'push_back' in 'del_line', which is of non-class type 'std::vector<int>()'
   26 |     if(flag == false) del_line.push_back(h);
      |                                ^~~~~~~~~
a.cc:37:31: error: request for member 'push_back' in 'del_row', which is of non-class type 'std::vector<int>()'
   37 |     if(flag == false) del_row.push_back(w);
      |                               ^~~~~~~~~
a.cc:42:18: error: no matching function for call to 'begin(std::vector<int> (&)())'
   42 |     for (int i : del_line) {
      |                  ^~~~~~~~
In file included from /usr/include/c++/14/bits/algorithmfwd.h:39,
                 from /usr/include/c++/14/bits/stl_algo.h:59,
                 from /usr/include/c++/14/algorithm:61,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/initializer_list:88:5: note: candidate: 'template<class _Tp> constexpr const _Tp* std::begin(initializer_list<_Tp>)'
   88 |     begin(initializer_list<_Tp> __ils) noexcept
      |     ^~~~~
/usr/include/c++/14/initializer_list:88:5: note:   template argument deduction/substitution failed:
a.cc:42:18: note:   mismatched types 'std::initializer_list<_Tp>' and 'std::vector<int> (*)()'
   42 |     for (int i : del_line) {
      |                  ^~~~~~~~
In file included from /usr/include/c++/14/string:53,
                 from /usr/include/c++/14/bitset:52,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/usr/include/c++/14/bits/range_access.h:52:5: note: candidate: 'template<class _Container> constexpr decltype (__cont.begin()) std::begin(_Container&)'
   52 |     begin(_Container& __cont) -> decltype(__cont.begin())
      |     ^~~~~
/usr/include/c++/14/bits/range_access.h:52:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/range_access.h: In substitution of 'template<class _Container> constexpr decltype (__cont.begin()) std::begin(_Container&) [with _Container = std::vector<int>()]':
a.cc:42:18:   required from here
   42 |     for (int i : del_line) {
      |                  ^~~~~~~~
/usr/include/c++/14/bits/range_access.h:52:50: error: request for member 'begin' in '__cont', which is of non-class type 'std::vector<int>()'
   52 |     begin(_Container& __cont) -> decltype(__cont.begin())
      |                                           ~~~~~~~^~~~~
/usr/include/c++/14/bits/range_access.h:63:5: note: candidate: 'template<class _Container> constexpr decltype (__cont.begin()) std::begin(const _Container&)'
   63 |     begin(const _Container& __cont) -> decltype(__cont.begin())
      |     ^~~~~
/usr/include/c++/14/bits/range_access.h:63:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/range_access.h: In substitution of 'template<class _Container> constexpr decltype (__cont.begin()) std::begin(const _Container&) [with _Container = std::vector<int>()]':
a.cc:42:18:   required from here
   42 |     for (int i : del_line) {
      |                  ^~~~~~~~
/usr/include/c++/14/bits/range_access.h:63:56: error: request for member 'begin' in '__cont', which is of non-class type 'std::vector<int>()'
   63 |     begin(const _Container& __cont) -> decltype(__cont.begin())
      |                                                 ~~~~~~~^~~~~
/usr/include/c++/14/bits/range_access.h:95:5: note: candidate: 'template<class _Tp, long unsigned int _Nm> constexpr _Tp* std::begin(_Tp (&)[_Nm])'
   95 |     begin(_Tp (&__arr)[_Nm]) noexcept
      |     ^~~~~
/usr/include/c++/14/bits/range_access.h:95:5: note:   template argument deduction/substitution failed:
a.cc:42:18: note:   mismatched types '_Tp [_Nm]' and 'std::vector<int>()'
   42 |     for (int i : del_line) {
      |                  ^~~~~~~~
In file included from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:166:
/usr/include/c++/14/valarray:1227:5: note: candidate: 'template<class _Tp> _Tp* std::begin(valarray<_Tp>&)'
 1227 |     begin(valarray<_Tp>& __va) noexcept
      |     ^~~~~
/usr/include/c++/14/valarray:1227:5: note:   template argument deduction/substitution failed:
a.cc:42:18: note:   mismatched types 'std::valarray<_Tp>' and 'std::vector<int>()'
   42 |     for (int i : del_line) {
      |                  ^~~~~~~~
/usr/include/c++/14/valarray:1238:5: note: candidate: 'template<class _Tp> const _Tp* std::begin(const valarray<_Tp>&)'
 1238 |     begin(const valarray<_Tp>& __va) noexcept
      |     ^~~~~
/usr/include/c++/14/valarray:1238:5: note:   template argument deduction/substitution failed:
a.cc:42:18: note:   mismatched types 'const std::valarray<_Tp>' and 'std::vector<int>()'
   42 |     for (int i : del_line) {
      |                  ^~~~~~~~
a.cc:42:18: error: no matching function for call to 'end(std::vector<int> (&)())'
/usr/include/c++/14/initializer_list:99:5: note: candidate: 'template<class _Tp> constexpr const _Tp* std::end(initializer_list<_Tp>)'
   99 |     end(initializer_list<_Tp> __ils) noexcept
      |     ^~~
/usr/include/c++/14/initializer_list:99:5: note:   template argument deduction/substitution failed:
a.cc:42:18: note:   mismatched types 'std::initializer_list<_Tp>' and 'std::vector<int> (*)()'
   42 |     for (int i : del_line) {
      |                  ^~~~~~~~
/usr/include/c++/14/bits/range_access.h:74:5: note: candidate: 'template<class _Container> constexpr decltype (__cont.end()) std::end(_Container&)'
   74 |     end(_Container& __cont) -> decltype(__cont.end())
      |     ^~~
/usr/include/c++/14/bits/range_access.h:74:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/range_access.h: In substitution of 'template<class _Container> constexpr decltype (__cont.end()) std::end(_Container&) [with _Container = std::vector<int>()]':
a.cc:42:18:   required from here
   42 |     for (int i : del_line) {
      |                  ^~~~~~~~
/usr/include/c++/14/bits/range_access.h:74:48: error: request for member 'end' in '__cont', which is of non-class type 'std::vector<int>()'
   74 |     end(_Container& __cont) -> decltype(__cont.end())
      |                                         ~~~~~~~^~~
/usr/include/c++/14/bits/range_access.h:85:5: note: candidate: 'template<class _Container> constexpr decltype (__cont.end()) std::end(const _Container&)'
   85 |     end(const _Container& __cont) -> decltype(__cont.end())
      |     ^~~
/usr/include/c++/14/bits/range_access.h:85:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/range_access.h: In substitution of 'template<class _Container> constexpr decltype (__cont.end()) std::end(const _Container&) [with _Container = std::vector<int>()]':
a.cc:42:18:   required from here
   42 |     for (int i : del_line) {
      |                  ^~~~~~~~
/usr/include/c++/14/bits/range_access.h:85:54: error: request for member 'end' in '__cont', which is of non-class type 'std::vector<int>()'
   85 |     end(const _Container& __cont) -> decltype(__cont.end())
      |                                               ~~~~~~~^~~
/usr/include/c++/14/bits/range_access.h:106:5: note: candidate: 'template<class _Tp, long unsigned int _Nm> constexpr _Tp* std::end(_Tp (&)[_Nm])'
  106 |     end(_Tp (&__arr)[_Nm]) noexcept
      |     ^~~
/usr/include/c++/14/bits/range_access.h:106:5: note:   template argument deduction/substitution failed:
a.cc:42:18: note:   mismatched types '_Tp [_Nm]' and 'std::vector<int>()'
   42 |     for (int i : del_line) {
      |                  ^~~~~~~~
/usr/include/c++/14/valarray:1249:5: note: candidate: 'template<class _Tp> _Tp* std::end(valarray<_Tp>&)'
 1249 |     end(valarray<_Tp>& __va) noexcept
      |     ^~~
/usr/include/c++/14/valarray:1249:5: note:   template argument deduction/substitution failed:
a.cc:42:18: note:   mismatched types 'std::valarray<_Tp>' and 'std::vector<int>()'
   42 |     for (int i : del_line) {
      |                  ^~~~~~~~
/usr/include/c++/14/valarray:1265:5: note: candidate: 'template<class _Tp> const _Tp* std::end(const valarray<_Tp>&)'
 1265 |     end(const valarray<_Tp>& __va) noexcept
      |     ^~~
/usr/include/c++/14/valarray:1265:5: note:   template argument deduction/substitution failed:
a.cc:42:18: note:   mismatched types 'const std::valarray<_Tp>' and 'std::vector<int>()'
   42 |     for (int i : del_line) {
      |                  ^~~~~~~~
a.cc:51:20: error: no matching function for call to 'begin(std::vector<int> (&)())'
   51 |       for (int j : del_row) {
      |                    ^~~~~~~
/usr/include/c++/14/initializer_list:88:5: note: candidate: 'template<class _Tp> constexpr const _Tp* std::begin(initializer_list<_Tp>)'
   88 |     begin(initializer_list<_Tp> __ils) noexcept
      |     ^~~~~
/usr/include/c++/14/initializer_list:88:5: note:   template argument deduction/substitution failed:
a.cc:51:20: note:   mismatched types 'std::initializer_list<_Tp>' and 'std::vector<int> (*)()'
   51 |       for (int j : del_row) {
      |                    ^~~~~~~
/usr/include/c++/14/bits/range_access.h:52:5: note: candidate: 'template<class _Container> constexpr decltype (__cont.begin()) std::begin(_Container&)'
   52 |     begin(_Container& __cont) -> decltype(__cont.begin())
      |     ^~~~~
/usr/include/c++/14/bits/range_access.h:52:5: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/range_access.h: In substitution of 'template<class _Container> constexpr decltype (__cont.begin()) std::begin(_C