Add eertree

Author: adamant-pwn

cp-algo/data_structures/eertree.hpp

@@ -0,0 +1,72 @@
+#ifndef CP_ALGO_DATA_STRUCTURES_EERTREE_HPP
+#define CP_ALGO_DATA_STRUCTURES_EERTREE_HPP
+#include <forward_list>
+#include <functional>
+#include <iostream>
+#include <vector>
+#include <string>
+#include "../bump_alloc.hpp"
+namespace cp_algo::data_structures {
+    template<int sigma = 26, char mch = 'a'>
+    struct eertree {
+        eertree(size_t q) {
+            q += 2;
+            s = std::string(q, -1);
+            len = par = link = std::vector(q, 0);
+            to.resize(q);
+            link[0] = 1;
+            len[1] = -1;
+        }
+        
+        int get_link(int v) const {
+            while(s[n - 1] != s[n - len[v] - 2]) {
+                v = link[v];
+            }
+            return v;
+        }
+        
+        int get(int v, int c) const {
+            for(int cu: to[v]) {
+                if(char(cu) == c) {
+                    return cu >> 8;
+                }
+            }
+            return 0;
+        }
+        
+        void add_letter(char c) {
+            c -= 'a';
+            s[n++] = c;
+            last = get_link(last);
+            if(!get(last, c)) {
+                int u = get(get_link(link[last]), c);
+                link[sz] = u;
+                par[sz] = last;
+                len[sz] = len[last] + 2;
+                to[last].emplace_front((sz++ << 8) | c);
+            }
+            last = get(last, c);
+        }
+        int sufpal(auto &&adjust) const {
+            return adjust(last);
+        }
+        int sufpal() const {
+            return sufpal(std::identity{});
+        }
+        void print(auto &&adjust) const {
+            std::cout << sz - 2 << "\n";
+            for(int i = 2; i < sz; i++) {
+                std::cout << adjust(par[i]) << ' ' << adjust(link[i]) << "\n";
+            }
+        }
+        void print() const {
+            print(std::identity{});
+        }
+    private:
+        std::vector<std::forward_list<int, bump_alloc<int>>> to;
+        std::vector<int> len, link, par;
+        std::string s;
+        int n = 1, sz = 2, last = 0;
+    };
+}
+#endif // CP_ALGO_DATA_STRUCTURES_EERTREE_HPP

verify/string/eertree.test.cpp

@@ -0,0 +1,43 @@
+// @brief Eertree
+#define PROBLEM "https://judge.yosupo.jp/problem/eertree"
+#pragma GCC optimize("Ofast,unroll-loops")
+#pragma GCC target("tune=native")
+#include "cp-algo/data_structures/eertree.hpp"
+#include <bits/stdc++.h>
+
+using namespace std;
+using namespace cp_algo::data_structures;
+
+int yosupo(int v) {
+    if(v == 1) {
+        return -1;
+    } else if(v > 1) {
+        return v - 1;
+    } else {
+        return 0;
+    }
+}
+
+void solve() {
+    string s;
+    cin >> s;
+    eertree me(size(s));
+    vector<int> lasts;
+    lasts.reserve(size(s));
+    for(auto c: s) {
+        me.add_letter(c);
+        lasts.push_back(me.sufpal(yosupo));
+    }
+    me.print(yosupo);
+    ranges::copy(lasts, ostream_iterator<int>(cout, " "));
+}
+
+signed main() {
+    //freopen("input.txt", "r", stdin);
+    ios::sync_with_stdio(0);
+    cin.tie(0);
+    int t = 1;
+    while(t--) {
+        solve();
+    }
+}