Language: C++

#include <stdio.h>
#include <vector>

using namespace std;

#define SIZE (5)
#define SET(t, x, y) (((t) |= (1 << ((y) * SIZE + (x)))))
#define CHECK(t, x, y) (((t) & ((1 << ((y) * SIZE + (x))))) != 0)

int ans;
unsigned int hash[1 << 25];

int numofbits5(unsigned int bits) {
  bits = (bits & 0x55555555) + (bits >> 1 & 0x55555555);
  bits = (bits & 0x33333333) + (bits >> 2 & 0x33333333);
  bits = (bits & 0x0f0f0f0f) + (bits >> 4 & 0x0f0f0f0f);
  bits = (bits & 0x00ff00ff) + (bits >> 8 & 0x00ff00ff);
  return (bits & 0x0000ffff) + (bits >>16 & 0x0000ffff);
}

int dfs(unsigned int field, vector<unsigned int>& table, int depth)
{
	if (field == 0){
		if (ans > depth){
			ans = depth;
		}
		return (0);
	}
	if (ans <= depth || hash[field] <= depth){
		return (0);
	}
	
	hash[field] = depth;
	
	for (int i = table.size() - 1; i >= 0; i--){
		if (numofbits5(field) > numofbits5(field ^ table[i])){
			dfs(field ^ table[i], table, depth + 1);
		}
	}
	
	return (0);
}


int main(void)
{
	unsigned int field;
	int n;
	vector<unsigned int> table;
	
	while (1){
		scanf("%d", &n);
		
		if (n == 0){
			break;
		}
		
		table.clear();
		memset(hash, -1, sizeof(hash));
		for (int y = 0; y < n; y++){
			for (int x = 0; x < n; x++){
				for (int i = 1; i <= n - y; i++){
					for (int j = 1; j <= n - x; j++){
					table.push_back(0);
					for (int dy = y; dy < y + i; dy++){
						for (int dx = x; dx < x + j; dx++){
							SET(table.back(), dx, dy);
						}
					}
					}
				}
			}
		}
		
		field = 0;
		ans = 0;
		for (int i = 0; i < n; i++){
			for (int j = 0; j < n; j++){
				int t;
				scanf("%d", &t);
				if (t == 1){
					SET(field, j, i);
					ans++;
				}
			}
		}
		
		ans = n * n / 2 + 1;
		
		dfs(field, table, 0);
		
		for (int i = 0; i < ans; i++){
			printf("myon");
		}
		puts("");
	}
	
	return (0);
}

Compiler output:
a.cc: In function 'int dfs(unsigned int, std::vector<unsigned int>&, int)':
a.cc:29:29: error: reference to 'hash' is ambiguous
   29 |         if (ans <= depth || hash[field] <= depth){
      |                             ^~~~
In file included from /usr/include/c++/14/bits/stl_bvector.h:65,
                 from /usr/include/c++/14/vector:67,
                 from a.cc:2:
/usr/include/c++/14/bits/functional_hash.h:59:12: note: candidates are: 'template<class _Tp> struct std::hash'
   59 |     struct hash;
      |            ^~~~
a.cc:11:14: note:                 'unsigned int hash [33554432]'
   11 | unsigned int hash[1 << 25];
      |              ^~~~
a.cc:33:9: error: reference to 'hash' is ambiguous
   33 |         hash[field] = depth;
      |         ^~~~
/usr/include/c++/14/bits/functional_hash.h:59:12: note: candidates are: 'template<class _Tp> struct std::hash'
   59 |     struct hash;
      |            ^~~~
a.cc:11:14: note:                 'unsigned int hash [33554432]'
   11 | unsigned int hash[1 << 25];
      |              ^~~~
a.cc: In function 'int main()':
a.cc:59:24: error: reference to 'hash' is ambiguous
   59 |                 memset(hash, -1, sizeof(hash));
      |                        ^~~~
/usr/include/c++/14/bits/functional_hash.h:59:12: note: candidates are: 'template<class _Tp> struct std::hash'
   59 |     struct hash;
      |            ^~~~
a.cc:11:14: note:                 'unsigned int hash [33554432]'
   11 | unsigned int hash[1 << 25];
      |              ^~~~
a.cc:59:41: error: reference to 'hash' is ambiguous
   59 |                 memset(hash, -1, sizeof(hash));
      |                                         ^~~~
/usr/include/c++/14/bits/functional_hash.h:59:12: note: candidates are: 'template<class _Tp> struct std::hash'
   59 |     struct hash;
      |            ^~~~
a.cc:11:14: note:                 'unsigned int hash [33554432]'
   11 | unsigned int hash[1 << 25];
      |              ^~~~
a.cc:59:17: error: 'memset' was not declared in this scope
   59 |                 memset(hash, -1, sizeof(hash));
      |                 ^~~~~~
a.cc:3:1: note: 'memset' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
    2 | #include <vector>
  +++ |+#include <cstring>
    3 |