ローリングハッシュ
(string/rolling-hash.hpp)

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• Last update: 2024-08-24 11:50:18+09:00
• Include: #include "string/rolling-hash.hpp"

使い方

• build(S) : 文字列Sのハッシュを返す
• query(hash,l,r) : hashを用いて[l,r)のハッシュ値を求める
• combine(h1,h2,h2len) : ハッシュ値h1とハッシュ値h2のものを連結する
• lcp(hash1,l,r,hash2,l,r) : hash1の[l,r)とhash2の[l,r)の最長共通接頭辞の長さを返す (二分探索を用いる)

Depends on

• template/alias.hpp
• template/debug.hpp
• template/func.hpp
• template/macro.hpp
• template/template.hpp
• template/util.hpp

Verified with

• test/yosupo/zalgorithm.test.cpp

Code

#pragma once
#include "../template/template.hpp"

struct RollingHash {
    static const uint64_t mod = (1ull << 61ull) - 1;
    vector<uint64_t> power;
    const uint64_t base;

    static inline uint64_t generate_base() {
        mt19937_64 engine(chrono::steady_clock::now().time_since_epoch().count());
        uniform_int_distribution<uint64_t> rand((uint64_t)1, (uint64_t)mod - 1);
        return rand(engine);
    }

    static inline uint64_t add(uint64_t a, uint64_t b) {
        if ((a += b) >= mod) a -= mod;
        return a;
    }

    static inline uint64_t mul(uint64_t a, uint64_t b) {
        __uint128_t c = (__uint128_t)a * b;
        return add(c >> 61, c & mod);
    }

    inline void expand(size_t sz) {
        if (power.size() < sz + 1) {
            int pre_sz = (int)power.size();
            power.resize(sz + 1);
            for (int i = pre_sz - 1; i < (int)sz; i++) {
                power[i + 1] = mul(power[i], base);
            }
        }
    }

    explicit RollingHash(uint64_t base = generate_base()) : base(base), power{1} {}

    vector<uint64_t> build(string S) {
        vector<uint64_t> hash(S.size() + 1);
        for (int i = 0; i < (int)S.size(); i++) {
            hash[i + 1] = add(mul(hash[i], base), S[i]);
        }
        return hash;
    }

    uint64_t query(const vector<uint64_t>& hash, int l, int r) {
        expand(r - l);
        return add(hash[r], mod - mul(hash[l], power[r - l]));
    }

    uint64_t combine(uint64_t h1, uint64_t h2, size_t h2len) {
        expand(h2len);
        return add(mul(h1, power[h2len]), h2);
    }

    int lcp(const vector<uint64_t>& hash1, int l1, int r1, const vector<uint64_t>& hash2, int l2, int r2) {
        int len = min(r1 - l1, r2 - l2);
        int ok = 0;
        int ng = len + 1;
        while (ng - ok > 1) {
            int mid = (ok + ng) / 2;
            if (query(hash1, l1, l1 + mid) == query(hash2, l2, l2 + mid))
                ok = mid;
            else
                ng = mid;
        }
        return ok;
    }
};

#line 2 "template/template.hpp"
#include <bits/stdc++.h>
#line 3 "template/macro.hpp"

#define overload3(_1, _2, _3, name, ...) name
#define all1(v) std::begin(v), std::end(v)
#define all2(v, a) std::begin(v), std::begin(v) + a
#define all3(v, a, b) std::begin(v) + a, std::begin(v) + b
#define all(...) overload3(__VA_ARGS__, all3, all2, all1)(__VA_ARGS__)
#define rall1(v) std::rbegin(v), std::rend(v)
#define rall2(v, a) std::rbegin(v), std::rbegin(v) + a
#define rall3(v, a, b) std::rbegin(v) + a, std::rbegin(v) + b
#define rall(...) overload3(__VA_ARGS__, rall3, rall2, rall1)(__VA_ARGS__)
#define elif else if
#define updiv(N, X) (((N) + (X) - 1) / (X))
#define sigma(a, b) (((a) + (b)) * ((b) - (a) + 1) / 2)
#define INT(...)     \
    int __VA_ARGS__; \
    scan(__VA_ARGS__)
#define LL(...)     \
    ll __VA_ARGS__; \
    scan(__VA_ARGS__)
#define STR(...)        \
    string __VA_ARGS__; \
    scan(__VA_ARGS__)
#define CHR(...)      \
    char __VA_ARGS__; \
    scan(__VA_ARGS__)
#define DOU(...)        \
    double __VA_ARGS__; \
    scan(__VA_ARGS__)
#define LD(...)     \
    ld __VA_ARGS__; \
    scan(__VA_ARGS__)
#define pb push_back
#define eb emplace_back
#line 3 "template/alias.hpp"

using ll = long long;
using ld = long double;
using pii = std::pair<int, int>;
using pll = std::pair<ll, ll>;
constexpr int inf = 1 << 30;
constexpr ll INF = 1LL << 60;
constexpr int dx[8] = {1, 0, -1, 0, 1, -1, 1, -1};
constexpr int dy[8] = {0, 1, 0, -1, 1, 1, -1, -1};
constexpr int mod = 998244353;
constexpr int MOD = 1e9 + 7;
#line 3 "template/func.hpp"

template <typename T>
inline bool chmax(T& a, T b) { return ((a < b) ? (a = b, true) : (false)); }
template <typename T>
inline bool chmin(T& a, T b) { return ((a > b) ? (a = b, true) : (false)); }
template <typename T, typename U>
std::ostream &operator<<(std::ostream &os, const std::pair<T, U> &p) {
    os << p.first << " " << p.second;
    return os;
}
template <typename T, typename U>
std::istream &operator>>(std::istream &is, std::pair<T, U> &p) {
    is >> p.first >> p.second;
    return is;
}
template <typename T>
std::ostream &operator<<(std::ostream &os, const std::vector<T> &v) {
    for (auto it = std::begin(v); it != std::end(v);) {
        os << *it << ((++it) != std::end(v) ? " " : "");
    }
    return os;
}
template <typename T>
std::istream &operator>>(std::istream &is, std::vector<T> &v) {
    for (T &in : v) {
        is >> in;
    }
    return is;
}
inline void scan() {}
template <class Head, class... Tail>
inline void scan(Head &head, Tail &...tail) {
    std::cin >> head;
    scan(tail...);
}
template <class T>
inline void print(const T &t) { std::cout << t << '\n'; }
template <class Head, class... Tail>
inline void print(const Head &head, const Tail &...tail) {
    std::cout << head << ' ';
    print(tail...);
}
template <class... T>
inline void fin(const T &...a) {
    print(a...);
    exit(0);
}
#line 3 "template/util.hpp"

struct IOSetup {
    IOSetup() {
        std::cin.tie(nullptr);
        std::ios::sync_with_stdio(false);
        std::cout.tie(0);
        std::cout << std::fixed << std::setprecision(12);
        std::cerr << std::fixed << std::setprecision(12);
    }
} IOSetup;
#line 3 "template/debug.hpp"

#ifdef LOCAL
#include <dump.hpp>
#else
#define debug(...)
#endif
#line 8 "template/template.hpp"
using namespace std;
#line 3 "string/rolling-hash.hpp"

struct RollingHash {
    static const uint64_t mod = (1ull << 61ull) - 1;
    vector<uint64_t> power;
    const uint64_t base;

    static inline uint64_t generate_base() {
        mt19937_64 engine(chrono::steady_clock::now().time_since_epoch().count());
        uniform_int_distribution<uint64_t> rand((uint64_t)1, (uint64_t)mod - 1);
        return rand(engine);
    }

    static inline uint64_t add(uint64_t a, uint64_t b) {
        if ((a += b) >= mod) a -= mod;
        return a;
    }

    static inline uint64_t mul(uint64_t a, uint64_t b) {
        __uint128_t c = (__uint128_t)a * b;
        return add(c >> 61, c & mod);
    }

    inline void expand(size_t sz) {
        if (power.size() < sz + 1) {
            int pre_sz = (int)power.size();
            power.resize(sz + 1);
            for (int i = pre_sz - 1; i < (int)sz; i++) {
                power[i + 1] = mul(power[i], base);
            }
        }
    }

    explicit RollingHash(uint64_t base = generate_base()) : base(base), power{1} {}

    vector<uint64_t> build(string S) {
        vector<uint64_t> hash(S.size() + 1);
        for (int i = 0; i < (int)S.size(); i++) {
            hash[i + 1] = add(mul(hash[i], base), S[i]);
        }
        return hash;
    }

    uint64_t query(const vector<uint64_t>& hash, int l, int r) {
        expand(r - l);
        return add(hash[r], mod - mul(hash[l], power[r - l]));
    }

    uint64_t combine(uint64_t h1, uint64_t h2, size_t h2len) {
        expand(h2len);
        return add(mul(h1, power[h2len]), h2);
    }

    int lcp(const vector<uint64_t>& hash1, int l1, int r1, const vector<uint64_t>& hash2, int l2, int r2) {
        int len = min(r1 - l1, r2 - l2);
        int ok = 0;
        int ng = len + 1;
        while (ng - ok > 1) {
            int mid = (ok + ng) / 2;
            if (query(hash1, l1, l1 + mid) == query(hash2, l2, l2 + mid))
                ok = mid;
            else
                ng = mid;
        }
        return ok;
    }
};

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