rt，代码：

#include <bits/stdc++.h>
#define int int64_t

const int maxn = 110;
const int maxm = (1 << 11);

int N, M;
char A;
int Farm[maxn];
int F[maxn][maxm][maxm];

std::vector<int> candidates;

auto popcount = [] (int x) {
	auto lowbit = [] (int x) {return x & (-x); };
	int cnt = 0;
	while (x) {
		x -= lowbit(x);
		cnt += 1;
	}
	return cnt;
};

signed main() {
	std::cin >> N >> M;
	
	for (int i = 1; i <= N; i++)
		for (int j = 1; j <= M; j++) {
			std::cin >> A;
			int a = (A == 'H');
			Farm[i] |= (a << (j - 1));
		}
	
	for (int j = 0; j < (1 << M); j++)
		if (!(j & (j << 1)) && !(j & (j >> 1)) && !(j & (j << 2)) && !(j & (j >> 2)))
			candidates.push_back(j);
	
	//for (int i = 1; i <= N; i++)
		//std::cout << Farm[i] << " \n"[i == N];
	
	for (int i = 1; i <= N; i++)
		for (auto j : candidates)
			if ((j & Farm[i]) == 0)
				for (auto k : candidates)
					for (auto p : candidates)
						if (!(j & k) && !(j & p) && !(k & p))
							F[i][j][k] = std::max(F[i - 1][k][p] + popcount(j), F[i][j][k]);
	
	//for (int i = 1; i <= N; i++)
		//for (int j = 0; j < (1 << M); j++)
			//std::cout << F[i][j] << " \n"[j == (1 << M) - 1];
	
	int res = 0;
	for (auto j : candidates)
		for (auto p : candidates)
			res = (res + F[N][j][p]);
	
	std::cout << res << std::endl;
	return 0;
}

题目： P2704 [NOI2001] 炮兵阵地。

记录：https://www.luogu.com.cn/record/151204518

CE 信息：

No valid executable file was produced by the compiler
./ccBvvssq.o: in function `_GLOBAL__sub_I_src':
src:(.text.startup+0x2f7): relocation truncated to fit: R_X86_64_PC32 against `.bss'
src:(.text.startup+0x311): relocation truncated to fit: R_X86_64_PC32 against `.bss'
collect2: 错误：ld 返回 1