verify/yosupo-enumerate_palindromes-manacher.test.cpp

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• Last update: 2025-07-03 00:41:25+09:00
• Problem: https://judge.yosupo.jp/problem/enumerate_palindromes
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Depends on

• Manacher's Algorithm（最長回文） (algorithm/String/manacher.hpp)

Code

#define PROBLEM "https://judge.yosupo.jp/problem/enumerate_palindromes"

#include <iostream>
#include <string>

#include "../algorithm/String/manacher.hpp"

int main() {
    std::string s;
    std::cin >> s;

    algorithm::Manacher manacher(s);

    const int n = s.size();
    for(int i = 0; i < n; ++i) {
        std::cout << 2 * manacher.odd_radius(i) - 1 << " ";
        if(i < n - 1) std::cout << 2 * manacher.even_radius(i) << " ";
    }
    std::cout << std::endl;
}

#line 1 "verify/yosupo-enumerate_palindromes-manacher.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/enumerate_palindromes"

#include <iostream>
#include <string>

#line 1 "algorithm/String/manacher.hpp"



/**
 * @brief Manacher's Algorithm（最長回文）
 * @docs docs/String/manacher.md
 */

#include <cassert>
#include <vector>

namespace algorithm {

// Manacher's Algorithm（最長回文）.
template <class Sequence>
class Manacher {
    int m_sz;  // m_sz:=(配列サイズ).
    // m_radius[2*k]:=(k文字目を中心とする奇数長の最長回文の半径),
    // m_radius[2*k+1]:=(k文字目とk+1文字目の間を中心とする偶数長の最長回文の半径).
    std::vector<int> m_radius;

public:
    // constructor. 引数はSTLのシーケンスコンテナ．O(|S|).
    Manacher() : Manacher(Sequence()) {}
    explicit Manacher(const Sequence &s) : m_sz(s.size()), m_radius(2 * s.size(), 0) {
        if(size() == 0) return;
        const int n = 2 * size() - 1;
        Sequence t(n, 0);
        for(int i = 0; i < size(); ++i) t[2 * i] = s[i];
        int i = 0, j = 0;
        while(i < n) {
            while(0 <= i - j and i + j < n and t[i - j] == t[i + j]) j++;
            m_radius[i] = j;
            int k = 1;
            while(0 <= i - k and i + k < n and k + m_radius[i - k] < j) {
                m_radius[i + k] = m_radius[i - k];
                k++;
            }
            i += k, j -= k;
        }
    }

    // 配列のサイズを返す．
    int size() const { return m_sz; }
    // k文字目を中心とする奇数長の最長回文の半径を返す．
    int odd_radius(int k) const {
        assert(0 <= k and k < size());
        return (m_radius[2 * k] + 1) / 2;
    }
    // k文字目とk+1文字目の間を中心とする偶数長の最長回文の半径を返す．
    int even_radius(int k) const {
        assert(0 <= k and k < size() - 1);
        return m_radius[2 * k + 1] / 2;
    }
    // 部分列s[l:r]が回文か判定する．
    bool is_palindrome(int l, int r) const {
        assert(0 <= l and l < r and r <= size());
        int mid = (l + r) / 2;
        if((r - l) & 1) return odd_radius(mid) >= (r - l + 1) / 2;
        return even_radius(mid) >= (r - l) / 2;
    }
};

}  // namespace algorithm


#line 7 "verify/yosupo-enumerate_palindromes-manacher.test.cpp"

int main() {
    std::string s;
    std::cin >> s;

    algorithm::Manacher manacher(s);

    const int n = s.size();
    for(int i = 0; i < n; ++i) {
        std::cout << 2 * manacher.odd_radius(i) - 1 << " ";
        if(i < n - 1) std::cout << 2 * manacher.even_radius(i) << " ";
    }
    std::cout << std::endl;
}

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