P3868 [TJOI2009] 猜数字

https://www.luogu.com.cn/record/89550624

Luogu/P3868/P3868.cpp

@@ -0,0 +1,59 @@
+#include <iostream>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int K = 15;
+
+int k;
+long long a[K], b[K];
+
+long long exgcd(long long a, long long b, long long &x, long long &y) {
+    if (!b) {
+        x = 1, y = 0;
+        return a;
+    }
+
+    long long g = exgcd(b, a % b, y, x);
+    y -= a / b * x;
+
+    return g;
+}
+
+long long CRT() {
+    long long mod = 1, ans = 0;
+
+    for (int i = 1; i <= k; i++) {
+        mod *= b[i];
+    }
+
+    for (int i = 1; i <= k; i++) {
+        long long m = mod / b[i], x, y;
+        exgcd(m, b[i], x, y);
+        ans = (ans + static_cast<__int128>(a[i]) * m * x % mod) % mod;
+    }
+
+    return (ans % mod + mod) % mod;
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> k;
+
+    for (int i = 1; i <= k; i++) {
+        cin >> a[i];
+    }
+
+    for (int i = 1; i <= k; i++) {
+        cin >> b[i];
+
+        a[i] = (a[i] % b[i] + b[i]) % b[i];
+    }
+
+    cout << CRT() << endl;
+
+    return 0;
+}