#1972. 【Public NOIP Round #5】青鱼和区间

https://sjzezoj.com/submission/72660

S2OJ/1972/1972.cpp

@@ -0,0 +1,46 @@
+#include <iostream>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 305;
+
+int n, p, f[N][N], d[N], p2[N * N];
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> p;
+
+    p2[0] = 1;
+
+    for (int i = 1; i <= n * n; i++) {
+        p2[i] = static_cast<long long>(p2[i - 1]) * 2 % p;
+    }
+
+    f[1][1] = 1;
+
+    for (int i = 2; i <= n; i++) {
+        f[i][1] = p2[(i - 1) * (i - 2) / 2];
+
+        for (int j = 2; j <= i; j++) {
+            for (int k = 1; k < i; k++) {
+                f[i][j] = (f[i][j] + static_cast<long long>(f[k][j - 1]) * p2[(i - k - 1) * (i - k - 2) / 2] % p) % p;
+            }
+        }
+    }
+
+    for (int i = 1; i <= n; i++) {
+        d[i] = p2[i * (i + 1) / 2];
+
+        for (int j = 1; j < i; j++) {
+            d[i] = ((d[i] - static_cast<long long>(f[i][j]) * d[j]) % p + p) % p;
+        }
+    }
+
+    cout << d[n] << endl;
+
+    return 0;
+}