P1896 [SCOI2005]互不侵犯

https://www.luogu.com.cn/record/76443655

Luogu/P1896/P1896.cpp

@@ -0,0 +1,48 @@
+#include <iostream>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+int n, k;
+int cnt, r[2005], s[2005];
+long long f[15][2005][105], ans;
+
+void dfs(int x, int sum, int len) {
+    if (len >= n) {
+        r[++cnt] = x;
+        s[cnt] = sum;
+        return;
+    }
+
+    dfs(x, sum, len + 1);
+    dfs(x + (1 << len), sum + 1, len + 2);
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+
+    cin >> n >> k;
+
+    dfs(0, 0, 0);
+
+    for (int i = 1; i <= cnt; i++) f[1][i][s[i]] = 1;
+
+    for (int i = 2; i <= n; i++) {
+        for (int j = 1; j <= cnt; j++) {
+            for (int p = 1; p <= cnt; p++) {
+                if ((r[j] & r[p]) || ((r[j] << 1) & r[p]) || (r[j] & (r[p] << 1))) continue;
+
+                for (int l = k; l >= s[j]; l--) {
+                    f[i][j][l] += f[i - 1][p][l - s[j]];
+                }
+            }
+        }
+    }
+
+    for (int i = 1; i <= cnt; i++) ans += f[n][i][k];
+
+    cout << ans << endl;
+
+    return 0;
+}