結果

問題 No.2858 Make a Palindrome
コンテスト
ユーザー hitonanode
提出日時 2024-08-25 13:35:58
言語 C++23
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 273 ms / 3,000 ms
コード長 9,173 bytes
コンパイル時間 2,145 ms
コンパイル使用メモリ 190,324 KB
実行使用メモリ 44,132 KB
最終ジャッジ日時 2024-08-25 13:36:16
合計ジャッジ時間 7,682 ms
ジャッジサーバーID
（参考情報） 		judge4 / judge5
このコードへのチャレンジ
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ファイルパターン 結果
other AC * 40
権限があれば一括ダウンロードができます

ソースコード

diff # 

#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <chrono>
#include <cmath>
#include <complex>
#include <deque>
#include <forward_list>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iostream>
#include <limits>
#include <list>
#include <map>
#include <memory>
#include <numeric>
#include <optional>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <tuple>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
using namespace std;
using lint = long long;
using pint = pair<int, int>;
using plint = pair<lint, lint>;
struct fast_ios { fast_ios(){ cin.tie(nullptr), ios::sync_with_stdio(false), cout << fixed << setprecision(20); }; } fast_ios_;
#define ALL(x) (x).begin(), (x).end()
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
template <typename T> bool chmax(T &m, const T q) { return m < q ? (m = q, true) : false; }
template <typename T> bool chmin(T &m, const T q) { return m > q ? (m = q, true) : false; }
const std::vector<std::pair<int, int>> grid_dxs{{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
int floor_lg(long long x) { return x <= 0 ? -1 : 63 - __builtin_clzll(x); }
template <class T1, class T2> T1 floor_div(T1 num, T2 den) { return (num > 0 ? num / den : -((-num + den - 1) / den)); }
template <class T1, class T2> std::pair<T1, T2> operator+(const std::pair<T1, T2> &l, const std::pair<T1, T2> &r) { return std::make_pair(l.first + r.first, l.second + r.second); }
template <class T1, class T2> std::pair<T1, T2> operator-(const std::pair<T1, T2> &l, const std::pair<T1, T2> &r) { return std::make_pair(l.first - r.first, l.second - r.second); }
template <class T> std::vector<T> sort_unique(std::vector<T> vec) { sort(vec.begin(), vec.end()), vec.erase(unique(vec.begin(), vec.end()), vec.end()); return vec; }
template <class T> int arglb(const std::vector<T> &v, const T &x) { return std::distance(v.begin(), std::lower_bound(v.begin(), v.end(), x)); }
template <class T> int argub(const std::vector<T> &v, const T &x) { return std::distance(v.begin(), std::upper_bound(v.begin(), v.end(), x)); }
template <class IStream, class T> IStream &operator>>(IStream &is, std::vector<T> &vec) { for (auto &v : vec) is >> v; return is; }

template <class OStream, class T> OStream &operator<<(OStream &os, const std::vector<T> &vec);
template <class OStream, class T, size_t sz> OStream &operator<<(OStream &os, const std::array<T, sz> &arr);
template <class OStream, class T, class TH> OStream &operator<<(OStream &os, const std::unordered_set<T, TH> &vec);
template <class OStream, class T, class U> OStream &operator<<(OStream &os, const pair<T, U> &pa);
template <class OStream, class T> OStream &operator<<(OStream &os, const std::deque<T> &vec);
template <class OStream, class T> OStream &operator<<(OStream &os, const std::set<T> &vec);
template <class OStream, class T> OStream &operator<<(OStream &os, const std::multiset<T> &vec);
template <class OStream, class T> OStream &operator<<(OStream &os, const std::unordered_multiset<T> &vec);
template <class OStream, class T, class U> OStream &operator<<(OStream &os, const std::pair<T, U> &pa);
template <class OStream, class TK, class TV> OStream &operator<<(OStream &os, const std::map<TK, TV> &mp);
template <class OStream, class TK, class TV, class TH> OStream &operator<<(OStream &os, const std::unordered_map<TK, TV, TH> &mp);
template <class OStream, class... T> OStream &operator<<(OStream &os, const std::tuple<T...> &tpl);

template <class OStream, class T> OStream &operator<<(OStream &os, const std::vector<T> &vec) { os << '['; for (auto v : vec) os << v << ','; os << ']'; return os; }
template <class OStream, class T, size_t sz> OStream &operator<<(OStream &os, const std::array<T, sz> &arr) { os << '['; for (auto v : arr) os << v << ','; os << ']'; return os; }
template <class... T> std::istream &operator>>(std::istream &is, std::tuple<T...> &tpl) { std::apply([&is](auto &&... args) { ((is >> args), ...);}, tpl); return is; }
template <class OStream, class... T> OStream &operator<<(OStream &os, const std::tuple<T...> &tpl) { os << '('; std::apply([&os](auto &&... args) { ((os << args << ','), ...);}, tpl); return os << ')'; }
template <class OStream, class T, class TH> OStream &operator<<(OStream &os, const std::unordered_set<T, TH> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <class OStream, class T> OStream &operator<<(OStream &os, const std::deque<T> &vec) { os << "deq["; for (auto v : vec) os << v << ','; os << ']'; return os; }
template <class OStream, class T> OStream &operator<<(OStream &os, const std::set<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <class OStream, class T> OStream &operator<<(OStream &os, const std::multiset<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <class OStream, class T> OStream &operator<<(OStream &os, const std::unordered_multiset<T> &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; }
template <class OStream, class T, class U> OStream &operator<<(OStream &os, const std::pair<T, U> &pa) { return os << '(' << pa.first << ',' << pa.second << ')'; }
template <class OStream, class TK, class TV> OStream &operator<<(OStream &os, const std::map<TK, TV> &mp) { os << '{'; for (auto v : mp) os << v.first << "=>" << v.second << ','; os << '}'; return os; }
template <class OStream, class TK, class TV, class TH> OStream &operator<<(OStream &os, const std::unordered_map<TK, TV, TH> &mp) { os << '{'; for (auto v : mp) os << v.first << "=>" << v.second << ','; os << '}'; return os; }
#ifdef HITONANODE_LOCAL
const string COLOR_RESET = "\033[0m", BRIGHT_GREEN = "\033[1;32m", BRIGHT_RED = "\033[1;31m", BRIGHT_CYAN = "\033[1;36m", NORMAL_CROSSED = "\033[0;9;37m", RED_BACKGROUND = "\033[1;41m", NORMAL_FAINT = "\033[0;2m";
#define dbg(x) std::cerr << BRIGHT_CYAN << #x << COLOR_RESET << " = " << (x) << NORMAL_FAINT << " (L" << __LINE__ << ") " << __FILE__ << COLOR_RESET << std::endl
#define dbgif(cond, x) ((cond) ? std::cerr << BRIGHT_CYAN << #x << COLOR_RESET << " = " << (x) << NORMAL_FAINT << " (L" << __LINE__ << ") " << __FILE__ << COLOR_RESET << std::endl : std::cerr)
#else
#define dbg(x) ((void)0)
#define dbgif(cond, x) ((void)0)
#endif

// Manacher's Algorithm: radius of palindromes
// Input: std::string or std::vector<T> of length N
// Output: std::vector<int> of size N
// Complexity: O(N)
// Sample:
// - `sakanakanandaka` -> [1, 1, 2, 1, 4, 1, 4, 1, 2, 2, 1, 1, 1, 2, 1]
// Reference: https://snuke.hatenablog.com/entry/2014/12/02/235837
template <typename T> std::vector<int> manacher(const std::vector<T> &S) {
    std::vector<int> res(S.size());
    int i = 0, j = 0;
    while (i < int(S.size())) {
        while (i - j >= 0 and i + j < int(S.size()) and S[i - j] == S[i + j]) j++;
        res[i] = j;
        int k = 1;
        while (i - k >= 0 and i + k < int(S.size()) and k + res[i - k] < j)
            res[i + k] = res[i - k], k++;
        i += k, j -= k;
    }
    return res;
}
std::vector<int> manacher(const std::string &S) {
    std::vector<char> v(S.size());
    for (int i = 0; i < int(S.size()); i++) v[i] = S[i];
    return manacher(v);
}

template <typename T>
std::vector<std::pair<int, int>> enumerate_palindromes(const std::vector<T> &vec) {
    std::vector<T> v;
    const int N = vec.size();
    for (int i = 0; i < N - 1; i++) {
        v.push_back(vec[i]);
        v.push_back(-1);
    }
    v.push_back(vec.back());
    const auto man = manacher(v);
    std::vector<std::pair<int, int>> ret;
    for (int i = 0; i < N * 2 - 1; i++) {
        if (i & 1) {
            int w = man[i] / 2;
            ret.emplace_back((i + 1) / 2 - w, (i + 1) / 2 + w);
        } else {
            int w = (man[i] - 1) / 2;
            ret.emplace_back(i / 2 - w, i / 2 + w + 1);
        }
    }
    return ret;
}

std::vector<std::pair<int, int>> enumerate_palindromes(const std::string &S) {
    std::vector<char> v(S.size());
    for (int i = 0; i < int(S.size()); i++) v[i] = S[i];
    return enumerate_palindromes<char>(v);
}

int solve(int M, string S) {
    const int N = S.size();

    const int K = 5;
    string U;

    const int inf = 1 << 30;
    int ret = inf;

    FOR(n, 1, K) {
        U += S;

        for (auto [l, r] : enumerate_palindromes(U)) {
            if (r - l >= M) return n;

            if (l == 0 or r == (int)U.size()) {
                if (n >= 3 and r - l > N * 2) {
                    int req = M - (r - l);
                    chmin(ret, n + (req + N * 2 - 1) / (N * 2) * 2);
                }
            }
        }
    }
    // U += S;


    if (ret == inf) ret = -1;

    return ret;
}

int main() {
    int T;
    cin >> T;
    while (T--) {
        int N, M;
        string S;
        cin >> N >> M >> S;
        cout << solve(M, S) << '\n';
    }
}
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