P4994 终于结束的起点

R38706118

problem/P4994/P4994.cpp

@@ -0,0 +1,37 @@
+// R38706118
+
+#include <bits/stdc++.h>
+
+using namespace std;
+
+long long a[10000000];
+
+long long dfib(long long x, long long m) {
+    if (a[x] != -1) {
+        return a[x];
+    }
+    if (x == 0) {
+        a[x] = 0 % m;
+        return 0;
+    }
+    if (x == 1) {
+        a[x] = 1 % m;
+        return 1;
+    }
+    a[x] = (dfib(x - 1, m) + dfib(x - 2, m)) % m;
+    return a[x];
+}
+
+int main() {
+    long long m;
+    memset(a, 0xff, sizeof(a));
+    cin >> m;
+    for (int i = 2; i < m * m; i++) {
+        // cout << i << ' ' << dfib(i, m) << endl;
+        if (dfib(i, m) == 0 && dfib(i + 1, m) == 1) {
+            cout << i;
+            break;
+        }
+    }
+    return 0;
+}