#1511. 【CSP七连测Day1】华二

https://sjzezoj.com/submission/56218

S2OJ/1511/1511.cpp

@@ -0,0 +1,95 @@
+#include <iostream>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 1e5 + 5;
+const int mod = 998244353;
+
+int n, ans = 1;
+int cnt1, cnt5, cnt7;
+int cnt2, cnt3, cnt236;
+int fac[N], inv[N], fac_inv[N];
+
+inline int C(int n, int m) {
+    return static_cast<long long>(fac[n]) * fac_inv[m] % mod * fac_inv[n - m] % mod;
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    fac[0] = 1;
+    for (int i = 1; i < N; i++) {
+        fac[i] = static_cast<long long>(fac[i - 1]) * i % mod;
+    }
+
+    inv[0] = inv[1] = 1;
+    for (int i = 2; i < N; i++) {
+        inv[i] = static_cast<long long>(mod - (mod / i)) * inv[mod % i] % mod;
+    }
+
+    fac_inv[0] = fac_inv[1] = 1;
+    for (int i = 2; i < N; i++) {
+        fac_inv[i] = static_cast<long long>(fac_inv[i - 1]) * inv[i] % mod;
+    }
+
+    cin >> n;
+
+    for (int i = 1, x; i <= n; i++) {
+        cin >> x;
+
+        switch (x) {
+            case 1: {
+                cnt1++;
+
+                break;
+            }
+
+            case 5: {
+                cnt5++;
+
+                break;
+            }
+
+            case 7: {
+                cnt7++;
+
+                break;
+            }
+
+            case 2:
+            case 4:
+            case 8: {
+                cnt2++;
+                cnt236++;
+
+                break;
+            }
+
+            case 3:
+            case 9: {
+                cnt3++;
+                cnt236++;
+
+                break;
+            }
+
+            case 6: {
+                cnt236++;
+                ans = static_cast<long long>(ans) * fac[cnt2 + cnt3] % mod * fac_inv[cnt2] % mod * fac_inv[cnt3] % mod;
+                cnt2 = cnt3 = 0;
+
+                break;
+            }
+        }
+    }
+
+    ans = static_cast<long long>(ans) * fac[cnt2 + cnt3] % mod * fac_inv[cnt2] % mod * fac_inv[cnt3] % mod;
+    ans = static_cast<long long>(ans) * fac[cnt1 + cnt236 + cnt5 + cnt7] % mod * fac_inv[cnt1] % mod * fac_inv[cnt236] % mod * fac_inv[cnt5] % mod * fac_inv[cnt7] % mod;
+
+    cout << ans << endl;
+
+    return 0;
+}