P2704 [NOI2001] 炮兵阵地

https://www.luogu.com.cn/record/76600647

Luogu/P2704/P2704.cpp

@@ -0,0 +1,86 @@
+#include <cstring>
+#include <iostream>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+int n, m, cnt, s[105], f[105][105][105], ans;
+std::pair<int, int> r[105];
+
+void dfs(int x, int sum, int len) {
+    if (len >= m) {
+        r[++cnt] = std::make_pair(x, sum);
+        return;
+    }
+
+    dfs(x, sum, len + 1);
+    dfs(x + (1 << len), sum + 1, len + 3);
+}
+
+bool check(int x, int y) {
+    return !(s[x] & y);
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+
+    cin >> n >> m;
+
+    for (int i = 1; i <= n; i++) {
+        for (int j = 1; j <= m; j++) {
+            char c;
+            cin >> c;
+
+            if (c == 'H') {
+                s[i] |= 1 << m - j;
+            }
+        }
+    }
+
+    dfs(0, 0, 0);
+
+    memset(f, 0xff, sizeof(f));
+    f[0][0][0] = 0;
+    for (int i = 1; i <= cnt; i++) {
+        if (check(1, r[i].first)) {
+            f[1][i][1] = r[i].second;
+
+            ans = std::max(ans, f[1][i][1]);
+        }
+    }
+
+    for (int i = 2; i <= n; i++) {
+        for (int j = 1; j <= cnt; j++) {
+            if (check(i, r[j].first)) {
+                for (int k = 1; k <= cnt; k++) {
+                    if (check(i - 1, r[k].first) && !(r[j].first & r[k].first)) {
+                        int last = 0;
+
+                        for (int l = 1; l <= cnt; l++) {
+                            if (~f[i - 1][k][l] && !(r[j].first & r[l].first) && check(i - 2, r[l].first)) {
+                                last = std::max(last, f[i - 1][k][l]);
+                            }
+                        }
+
+                        f[i][j][k] = std::max(f[i][j][k], last + r[j].second);
+                    }
+                }
+            }
+        }
+    }
+
+    for (int i = 1; i <= cnt; i++) {
+        if (check(n, r[i].first)) {
+            for (int j = 1; j <= cnt; j++) {
+                if (check(n - 1, r[j].first) && !(r[i].first & r[j].first)) {
+                    ans = std::max(ans, f[n][i][j]);
+                }
+            }
+        }
+    }
+
+    cout << ans << endl;
+
+    return 0;
+}