Language: C++

#include<bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> PII;
typedef pair<int, PII> PIP;

const int MM = 1e9 + 7;
const double eps = 1e-8;
const int MAXN = 1000 + 10;

int n, m;

void prework(){

}

void read(){

}

char CH[5] = {'R', 'Y', 'G', 'B', 'R'};
int f[MAXN][MAXN];
int g[MAXN][MAXN][5];

const ll P2 = 312394189;
const ll P3 = 468591283;

template<> struct hash<PIP>(){
	size_t operator()(const &PIP x) const {
		return (x.first + (x.second.first * P2 + x.second.second) % MM * P3) % MM;
	}
}

unordered_set<PIP> st;
int vis[MAXN][MAXN];

int ADD(int x, int y, int col, int cnt){
	st.erase(PIP(g[x][y][4], PII(x, y)));
	if (g[x][y][col] == 0){
		g[x][y][4]--;
	}
	g[x][y][col] += cnt;
	if (g[x][y][col] == 0){
		g[x][y][4]++;
	}
	st.insert(PIP(g[x][y][4], PII(x, y)));
	if (g[x][y][4] == 0) return 0;
	else return 1;
}

int d;

int dfs(int dep){
	if (dep == n * m + 1){
		for(int i = 1; i <= n; i++){
			for (int j = 1; j <= m; j++)
				putchar(CH[f[i][j]]);
			puts("");
		}
		return 1;
	}
	PIP p = *(st.begin());
	st.erase(st.begin());
	int x = p.second.first;
	int y = p.second.second;
	//cout << dep << ' ' << x << ' ' << y << endl;
	vis[x][y] = 1;
	for (int i = 0; i < 4; i++)
		if ((g[x][y][i] == 0)){
			f[x][y] = i;
			int flag = 1;
			for (int dx = -d; dx <= d; dx++){
				int dy = d - abs(dx);
				if (1 <= x + dx && x + dx <= n && y + dy >= 1 && y + dy <= m && !vis[x + dx][y + dy]){
					flag &= ADD(x + dx, y + dy, i, 1);
				}
				if (dy != 0) {
					dy = -dy;
					if (1 <= x + dx && x + dx <= n && y + dy >= 1 && y + dy <= m && !vis[x + dx][y + dy]){
						flag &= ADD(x + dx, y + dy, i, 1);
					}
				}
			}
			if (flag) if (dfs(dep + 1)) return 1;
			for (int dx = -d; dx <= d; dx++){
				int dy = d - abs(dx);
				if (1 <= x + dx && x + dx <= n && y + dy >= 1 && y + dy <= m && !vis[x + dx][y + dy]){
					ADD(x + dx, y + dy, i, -1);
				}
				if (dy != 0) {
					dy = -dy;
					if (1 <= x + dx && x + dx <= n && y + dy >= 1 && y + dy <= m && !vis[x + dx][y + dy]){
						ADD(x + dx, y + dy, i, -1);
					}
				}
			}
		}
	vis[x][y] = 0;
	st.insert(p);
	return 0;
}

int px[8] = {-2, -1, -1, 0, 0, 1, 1, 2};
int py[8] = {0, -1, 1, -2, 2, -1, 1, 0};

int p[5000][5000];

void solve(int casi){
//	cout << "Case #" << casi << ": ";
	scanf("%d%d%d", &n, &m, &d);
	for (int i = 1; i <= n; i++)
		for (int j = 1; j <= m; j++){
			st.insert(PIP(4, PII(i, j)));
			g[i][j][4] = 4;
			vis[i][j] = 0;
		}
	if (d <= 5000) dfs(1);
	else{
		if (d & 1){
			for (int i = 1; i <= n; i++){
				for (int j = 1; j <= m; j++)
					putchar((i + j) & 1 ? 'R' : 'B');
				puts("");
			}
		}
		else{
//       13 14
//    22 23 24 25
// 31 32 33 34 35 36
//    42 43	44 45
//       53 54
// -2    3 4
// -1    2 5
			queue<PII> Q;
			int dd = d / 2;
			int bias = d;
			for (int i = -dd + 1; i <= dd - 1; i++){
				for (int j = 1 + (abs(i)); j <= d - abs(i); j++){
					p[bias + i][bias + j] = 1;
					Q.push(PII(bias + i, bias + j));
				}
			}
			for (int i = -dd + 1; i <= dd - 1; i++){
				for (int j = 1 + (abs(i)); j <= d - abs(i); j++){
					p[bias + i][bias + j + d] = 2;
					Q.push(PII(bias + i, bias + j + d));
				}
			}
			for (int i = -dd + 1; i <= dd - 1; i++){
				for (int j = 1 + (abs(i)); j <= d - abs(i); j++){
					p[bias + i - dd][bias + j + dd] = 3;
					Q.push(PII(bias + i - dd, bias + j + dd));
				}
			}
			for (int i = -dd + 1; i <= dd - 1; i++){
				for (int j = 1 + (abs(i)); j <= d - abs(i); j++){
					p[bias + i + dd][bias + j + dd] = 4;
					Q.push(PII(bias + i + dd, bias + j + dd));
				}
			}
			while(!Q.empty()){
				int x = Q.front().first, y = Q.front().second;
				Q.pop();
				for (int k = 0; k < 8; k++){
					int xx = x + px[k] * d;
					int yy = y + py[k] * d;
					if (1 <= xx && xx <= n && 1 <= yy && yy <= m && p[xx][yy] == 0){
						p[xx][yy] = p[x][y];
						Q.push(PII(xx, yy));
					}
				}
			}
			for (int i = 1; i <= n; i++){
				for (int j = 1; j <= m; j++)
					putchar(CH[p[i][j]]);
				puts("");
			}
		}
	}
}

void printans(){

}


int main(){
//	std::ios::sync_with_stdio(false);
	prework();
	int T = 1;
//	cin>>T;
	for(int i = 1; i <= T; i++){
		read();
		solve(i);
		printans();
	}
	return 0;
}

Compiler output:
a.cc:30:29: error: expected unqualified-id before ')' token
   30 | template<> struct hash<PIP>(){
      |                             ^
a.cc:36:20: error: use of deleted function 'std::unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set() [with _Value = std::pair<int, std::pair<int, int> >; _Hash = std::hash<std::pair<int, std::pair<int, int> > >; _Pred = std::equal_to<std::pair<int, std::pair<int, int> > >; _Alloc = std::allocator<std::pair<int, std::pair<int, int> > >]'
   36 | unordered_set<PIP> st;
      |                    ^~
In file included from /usr/include/c++/14/unordered_set:41,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:189,
                 from a.cc:1:
/usr/include/c++/14/bits/unordered_set.h:142:7: note: 'std::unordered_set<_Value, _Hash, _Pred, _Alloc>::unordered_set() [with _Value = std::pair<int, std::pair<int, int> >; _Hash = std::hash<std::pair<int, std::pair<int, int> > >; _Pred = std::equal_to<std::pair<int, std::pair<int, int> > >; _Alloc = std::allocator<std::pair<int, std::pair<int, int> > >]' is implicitly deleted because the default definition would be ill-formed:
  142 |       unordered_set() = default;
      |       ^~~~~~~~~~~~~
/usr/include/c++/14/bits/unordered_set.h:142:7: error: use of deleted function 'std::_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::_Hashtable() [with _Key = std::pair<int, std::pair<int, int> >; _Value = std::pair<int, std::pair<int, int> >; _Alloc = std::allocator<std::pair<int, std::pair<int, int> > >; _ExtractKey = std::__detail::_Identity; _Equal = std::equal_to<std::pair<int, std::pair<int, int> > >; _Hash = std::hash<std::pair<int, std::pair<int, int> > >; _RangeHash = std::__detail::_Mod_range_hashing; _Unused = std::__detail::_Default_ranged_hash; _RehashPolicy = std::__detail::_Prime_rehash_policy; _Traits = std::__detail::_Hashtable_traits<true, true, true>]'
In file included from /usr/include/c++/14/bits/unordered_map.h:33,
                 from /usr/include/c++/14/unordered_map:41,
                 from /usr/include/c++/14/functional:63,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53:
/usr/include/c++/14/bits/hashtable.h:539:7: note: 'std::_Hashtable<_Key, _Value, _Alloc, _ExtractKey, _Equal, _Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::_Hashtable() [with _Key = std::pair<int, std::pair<int, int> >; _Value = std::pair<int, std::pair<int, int> >; _Alloc = std::allocator<std::pair<int, std::pair<int, int> > >; _ExtractKey = std::__detail::_Identity; _Equal = std::equal_to<std::pair<int, std::pair<int, int> > >; _Hash = std::hash<std::pair<int, std::pair<int, int> > >; _RangeHash = std::__detail::_Mod_range_hashing; _Unused = std::__detail::_Default_ranged_hash; _RehashPolicy = std::__detail::_Prime_rehash_policy; _Traits = std::__detail::_Hashtable_traits<true, true, true>]' is implicitly deleted because the default definition would be ill-formed:
  539 |       _Hashtable() = default;
      |       ^~~~~~~~~~
/usr/include/c++/14/bits/hashtable.h:539:7: error: use of deleted function 'std::__detail::_Hashtable_base<_Key, _Value, _ExtractKey, _Equal, _Hash, _RangeHash, _Unused, _Traits>::_Hashtable_base() [with _Key = std::pair<int, std::pair<int, int> >; _Value = std::pair<int, std::pair<int, int> >; _ExtractKey = std::__detail::_Identity; _Equal = std::equal_to<std::pair<int, std::pair<int, int> > >; _Hash = std::hash<std::pair<int, std::pair<int, int> > >; _RangeHash = std::__detail::_Mod_range_hashing; _Unused = std::__detail::_Default_ranged_hash; _Traits = std::__detail::_Hashtable_traits<true, true, true>]'
In file included from /usr/include/c++/14/bits/hashtable.h:35:
/usr/include/c++/14/bits/hashtable_policy.h:1731:7: note: 'std::__detail::_Hashtable_base<_Key, _Value, _ExtractKey, _Equal, _Hash, _RangeHash, _Unused, _Traits>::_Hashtable_base() [with _Key = std::pair<int, std::pair<int, int> >; _Value = std::pair<int, std::pair<int, int> >; _ExtractKey = std::__detail::_Identity; _Equal = std::equal_to<std::pair<int, std::pair<int, int> > >; _Hash = std::hash<std::pair<int, std::pair<int, int> > >; _RangeHash = std::__detail::_Mod_range_hashing; _Unused = std::__detail::_Default_ranged_hash; _Traits = std::__detail::_Hashtable_traits<true, true, true>]' is implicitly deleted because the default definition would be ill-formed:
 1731 |       _Hashtable_base() = default;
      |       ^~~~~~~~~~~~~~~
/usr/include/c++/14/bits/hashtable_policy.h:1731:7: error: use of deleted function 'std::__detail::_Hash_code_base<_Key, _Value, _ExtractKey, _Hash, _RangeHash, _Unused, __cache_hash_code>::_Hash_code_base() [with _Key = std::pair<int, std::pair<int, int> >; _Value = std::pair<int, std::pair<int, int> >; _ExtractKey = std::__detail::_Identity; _Hash = std::hash<std::pair<int, std::pair<int, int> > >; _RangeHash = std::__detail::_Mod_range_hashing; _Unused = std::__detail::_Default_ranged_hash; bool __cache_hash_code = true]'
/usr/include/c++/14/bits/hashtable_policy.h: In instantiation of 'std::__detail::_Hashtable_ebo_helper<_Nm, _Tp, true>::_Hashtable_ebo_helper() [with int _Nm = 1; _Tp = std::hash<std::pair<int, std::pair<int, int> > >]':
/usr/include/c++/14/bits/hashtable_policy.h:1328:7:   required from here
 1328 |       _Hash_code_base() = default;
      |       ^~~~~~~~~~~~~~~
/usr/include/c++/14/bits/hashtable_policy.h:1245:49: error: use of deleted function 'std::hash<std::pair<int, std::pair<int, int> > >::hash()'
 1245 |       _Hashtable_ebo_helper() noexcept(noexcept(_Tp())) : _Tp() { }
      |                                                 ^~~~~
In file included from /usr/include/c++/14/string_view:50,
                 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 /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:52:
/usr/include/c++/14/bits/functional_hash.h:102:12: note: 'std::hash<std::pair<int, std::pair<int, int> > >::hash()' is implicitly deleted because the default definition would be ill-formed:
  102 |     struct hash : __hash_enum<_Tp>
      |            ^~~~
/usr/include/c++/14/bits/functional_hash.h:102:12: error: no matching function for call to 'std::__hash_enum<std::pair<int, std::pair<int, int> >, false>::__hash_enum()'
/usr/include/c++/14/bits/functional_hash.h:83:7: note: candidate: 'std::__hash_enum<_Tp, <anonymous> >::__hash_enum(std::__hash_enum<_Tp, <anonymous> >&&) [with _Tp = std::pair<int, std::pair<int, int> >; bool <anonymous> = false]'
   83 |       __hash_enum(__hash_enum&&);
      |       ^~~~~~~~~~~
/usr/include/c++/14/bits/functional_hash.h:83:7: note:   candidate expects 1 argument, 0 provided
/usr/include/c++/14/bits/functional_hash.h:102:12: error: 'std::__hash_enum<_Tp, <anonymous> >::~__hash_enum() [with _Tp = std::pair<int, std::pair<int, int> >; bool <anonymous> = false]' is private within this context
  102 |     struct hash : __hash_enum<_Tp>
      |            ^~~~
/usr/include/c++/14/bits/functional_hash.h:84:7: note: declared private here
   84 |       ~__hash_enum();
      |       ^
/usr/include/c++/14/bits/hashtable_policy.h:1245:49: note: use '-fdiagnostics-all-candidates' to display considered candidates
 1245 |       _Hashtable_ebo_helper() noexcept(noexcept(_Tp())) : _Tp() { }
      |                                                 ^~~~~
/usr/include/c++/14/bits/hashtable_policy.h:1328:7: note: 'std::__detail::_Hash_code_base<_Key, _Value, _ExtractKey, _Hash, _RangeHash, _Unused, __cache_hash_code>::_Hash_code_base() [with _Key = std::pair<int, std::pair<int, int> >; _Value = std::pair<int, std::pair<int, int> >; _ExtractKey = std::__detail::_Identity; _Hash = std::hash<std::pair<int, std::pair<int, int> > >; _RangeHash = std::__detail::_Mod_range_hashing; _Unused = std::__detail::_Default_ranged_hash; bool __cache_hash_code = true]' is implicitly deleted because the default definition would be ill-formed:
 1328 |       _Hash_code_base() = default;
      |       ^~~~~~~~~~~~~~~
/usr/include/c++/14/bits/hashtable_policy.h:1328:7: error: use of deleted function 'std::__detail::_Hashtable_ebo_helper<1, std::hash<std::pair<int, std::pair<int, int> > >, true>::~_Hashtable_ebo_helper()'
/usr/include/c++/14/bits/hashtable_policy.h:1242:12: note: 'std::__detail::_Hashtable_ebo_helper<1, std::hash<std::pair<int, std::pair<int, int> > >, true>::~_Hashtable_ebo_helper()' is implicitly deleted because the default definition would be ill-formed:
 1242 |     struct _Hashtable_ebo_helper<_Nm, _Tp, true>
      |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/hashtable_policy.h:1242:12: error: use of deleted function 'std::hash<std::pair<int, std::pair<int, int> > >::~hash()'
/usr/include/c++/14/bits/functional_hash.h:102:12: note: 'std::hash<std::pair<int, std::pair<int, int> > >::~hash()' is implicitly deleted because the default definition would be ill-formed:
  102 |     struct hash : __hash_enum<_Tp>
      |            ^~~~
/usr/include/c++/14/bits/functional_hash.h:102:12: error: 'std::__hash_enum<_Tp, <anonymous> >::~__hash_enum() [with _Tp = std::pair<int, std::pair<int, int> >; bool <anonymous> = false]' is private within this context
/usr/include/c++/14/bits/functional_hash.h:84:7: note: declared private here
   84 |       ~__hash_enum();
      |       ^
/usr/include/c++/14/bits/hashtable_policy.h:1731:7: note: use '-fdiagnostics-all-candidates' to display considered candidates
 1731 |       _Hashtable_base() = default;
      |       ^~~~~~~~~~~~~~~
/usr/include/c++/14/bits/hashtable_policy.h:1731:7: error: use of deleted function 'std::__detail::_Hash_code_base<std::pair<int, std::pair<int, int> >, std::pair<int, std::pair<int, int> >, std::__detail::_Identity, std::hash<std::pair<int, std::pair<int, int> > >, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, true>::~_Hash_code_base()'
/usr/include/c++/14/bits/hashtable_policy.h:1306:12: note: 'std::__detail::_Hash_code_base<std::pair<int, std::pair<int, int> >, std::pair<int, std::pair<int, int> >, std::__detail::_Identity, std::hash<std::pair<int, std::pair<in