#1663. 【2022.10.19 联考】火柴棍

https://sjzezoj.com/submission/61028

S2OJ/1663/1663.cpp

@@ -0,0 +1,68 @@
+#include <iostream>
+#include <cmath>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 1e5 + 5;
+const int mod = 998244853;
+
+int t, n, p[N], p1[N];
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    p1[0] = 1;
+    for (int i = 1; i <= 100000; i++) {
+        p[i] = (static_cast<long long>(p[i - 1]) * 10 % mod + 8) % mod;
+        p1[i] = static_cast<long long>(p1[i - 1]) * 10 % mod;
+    }
+
+    cin >> t;
+
+    while (t--) {
+        cin >> n;
+
+        int l = std::ceil(1.0 * n / 7);
+
+        if (n == 1) {
+            cout << -1 << endl;
+        } else if (n == 2) {
+            cout << 1 << endl;
+        } else if (n == 3) {
+            cout << 7 << endl;
+        } else if (n == 4) {
+            cout << 4 << endl;
+        } else if (n == 5) {
+            cout << 2 << endl;
+        } else if (n == 6) {
+            cout << 0 << endl;
+        } else if (n == 7) {
+            cout << 8 << endl;
+        } else if (n == 8) {
+            cout << 10 << endl;
+        } else if (n == 9) {
+            cout << 18 << endl;
+        } else if (n == 10) {
+            cout << 22 << endl;
+        } else if (n % 7 == 0) {
+            cout << p[l] << endl;
+        } else if (n % 7 == 1) {
+            cout << (static_cast<long long>(l - 2 > 0 ? p[l - 2] : 0) + static_cast<long long>(p1[l - 1])) % mod << endl;
+        } else if (n % 7 == 2) {
+            cout << (static_cast<long long>(l - 1 > 0 ? p[l - 1] : 0) + static_cast<long long>(p1[l - 1])) % mod << endl;
+        } else if (n % 7 == 3) {
+            cout << (static_cast<long long>(l - 3 > 0 ? p[l - 3] : 0) + static_cast<long long>(p1[l - 1]) * 2 % mod) % mod << endl;
+        } else if (n % 7 == 4) {
+            cout << (static_cast<long long>(l - 2 > 0 ? p[l - 2] : 0) + static_cast<long long>(p1[l - 1]) * 2 % mod) % mod << endl;
+        } else if (n % 7 == 5) {
+            cout << (static_cast<long long>(l - 1 > 0 ? p[l - 1] : 0) + static_cast<long long>(p1[l - 1]) * 2 % mod) % mod << endl;
+        } else {  // n % 7 == 6
+            cout << (static_cast<long long>(l - 1 > 0 ? p[l - 1] : 0) + static_cast<long long>(p1[l - 1]) * 6 % mod) % mod << endl;
+        }
+    }
+
+    return 0;
+}