P5446 [THUPC2018]绿绿和串串

https://www.luogu.com.cn/record/87863322

Luogu/P5446/P5446.cpp

@@ -0,0 +1,84 @@
+#include <iostream>
+#include <string>
+#include <vector>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+std::vector<int> manacher(const std::string &_s) {
+    int n = _s.size();
+    std::string s(n * 2 + 3, '#');
+
+    for (int i = 0; i < n; i++) {
+        s[i * 2 + 2] = _s[i];
+    }
+
+    s[0] = '^';
+    s[n * 2 + 2] = '$';
+
+    std::vector<int> p(s.size(), 1);
+
+    for (int i = 1, mid = 0, r = 0; i <= n * 2 + 1; i++) {
+        p[i] = i < r ? std::min(p[mid * 2 - i], r - i) : 1;
+
+        while (s[i - p[i]] == s[i + p[i]]) p[i]++;
+
+        if (i + p[i] - 1 > r) {
+            r = i + p[i] - 1;
+            mid = i;
+        }
+    }
+
+    for (int i = 0; i < n; i++) {
+        p[i] = p[i * 2 + 2] / 2;
+    }
+
+    p.resize(n);
+
+    return p;
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    int t;
+
+    cin >> t;
+
+    while (t--) {
+        std::string s;
+
+        cin >> s;
+
+        int n = s.size();
+
+        if (n == 1) {
+            cout << 1 << endl;
+
+            continue;
+        }
+
+        auto p = manacher(s);
+        std::vector<int> ans(n);
+
+        for (int i = n - 1; i >= 0; --i) {
+            if (i * 2 < n) {
+                ans[i] = (p[i] >= i + 1) && ans[i * 2];
+            } else {
+                ans[i] = p[i] >= n - i;
+            }
+        }
+
+        for (int i = 0; i < n; ++i) {
+            if (ans[i]) {
+                cout << (i + 1) << ' ';
+            }
+        }
+
+        cout << endl;
+    }
+
+    return 0;
+}