141. 周期

https://www.acwing.com/problem/content/submission/code_detail/13336130/

AcWing/141/141.cpp

@@ -0,0 +1,41 @@
+#include <iostream>
+#include <string>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 1e6 + 5;
+
+int t, n, next[N];
+std::string s;
+
+int main() {
+    std::ios::sync_with_stdio(false);
+
+    while (cin >> n, n) {
+        cout << "Test case #" << ++t << endl;
+
+        cin >> s;
+
+        s = ' ' + s;
+
+        next[1] = 0;
+        for (int i = 2, j = 0; i <= n; i++) {
+            while (j && s[i] != s[j + 1]) j = next[j];
+            if (s[i] == s[j + 1]) j++;
+            next[i] = j;
+        }
+
+        for (int i = 2; i <= n; i++) {
+            int len = i - next[i];
+            if (i % len == 0 && i / len > 1) {
+                cout << i << ' ' << i / len << endl;
+            }
+        }
+
+        cout << endl;
+    }
+
+    return 0;
+}