結果

問題 No.765 ukuku 2
ユーザー paruki
提出日時 2018-12-25 09:40:47
言語 C++14
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 245 ms / 3,000 ms
コード長 2,651 bytes
コンパイル時間 1,833 ms
コンパイル使用メモリ 174,104 KB
実行使用メモリ 16,256 KB
最終ジャッジ日時 2024-10-01 13:15:09
合計ジャッジ時間 7,700 ms
ジャッジサーバーID
（参考情報） 		judge4 / judge3
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
sample AC * 2
other AC * 48
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 #
プレゼンテーションモードにする

#define _USE_MATH_DEFINES
#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define MT make_tuple
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
#define RT return
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;
using vll = vector<ll>;
struct RollingHash {
    static const int C = 31, C2 = 29, P = 1000000007, P2 = 1000000009;
    int _n;
    vector<long long> pw, pw2, hs, hs2;
    RollingHash() {}
    RollingHash(const string &st)
        :_n((int)st.size()), pw(_n + 1), pw2(_n + 1), hs(_n + 1), hs2(_n + 1)
    {
        pw[0] = pw2[0] = 1;
        rep(i, _n) {
            pw[i + 1] = (pw[i] * C) % P;
            pw2[i + 1] = (pw2[i] * C2) % P2;
            hs[i + 1] = (C*hs[i] + st[i]) % P;
            hs2[i + 1] = (C2*hs2[i] + st[i]) % P2;
        }
    }
    // [l, r)
    pii getHash(int l, int r) {
        int res, res2;
        res = (hs[r] - hs[l] * pw[r - l]) % P;
        res2 = (hs2[r] - hs2[l] * pw2[r - l]) % P2;
        if (res < 0)res += P;
        if (res2 < 0)res2 += P2;
        return mp(res, res2);
    }
};
string S;
int N;
void solve() {
    cin >> S;
    N = sz(S);
    auto T = S;
    reverse(all(T));
    RollingHash hsh(S), rev(T);
    auto f = [&](int ml, int mr, int x) {
        auto p = hsh.getHash(ml - x, ml);
        auto q = rev.getHash(N - (mr + x), N - mr);
        return p == q;
    };
    int ans = 0;
    rep(ml, N) FOR(mr, ml, ml + 2) {
        int ok = 0, ng = min(ml, N - mr) + 1;
        while (ng - ok > 1) {
            int x = (ok + ng) / 2;
            (f(ml, mr, x) ? ok : ng) = x;
        }
        int l = ml - ok, r = mr + ok;
        if (r - l == N)continue;
        smax(ans, r - l);
        if (l > 1) {
            ok = 0, ng = min(l - 1, N - r) + 1;
            while (ng - ok > 1) {
                int x = (ok + ng) / 2;
                (f(l - 1, r, x) ? ok : ng) = x;
            }
            smax(ans, r - l + ok * 2);
        }
        if (r < N) {
            ok = 0, ng = min(l, N - (r + 1)) + 1;
            while (ng - ok > 1) {
                int x = (ok + ng) / 2;
                (f(l, r + 1, x) ? ok : ng) = x;
            }
            smax(ans, r - l + ok * 2);
        }
    }
    cout << ans << endl;
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(15);
    solve();
    return 0;
}
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