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RollingHash.hpp
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RollingHash.hpp
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#pragma once
#include "../template/template.hpp"
namespace lib {
using namespace std;
struct RollingHash {
using ull = unsigned long long;
RollingHash(const string& s = "") {
build(s);
}
ull get(int l, int r) {
assert(0 <= l && l <= r && r <= n);
return cal(inner_hash[r] + buf - mul(inner_hash[l], pow_base[r - l]));
}
static ull get_hash(const string& s) {
int len = s.size();
set_hash();
extend_pow_base(len);
ull res = 0;
rep(i, 0, len) res = cal(mul(res, BASE) + s[i]);
return res;
}
static ull concat(const ull& hash1, const ull& hash2, const int& len2) {
return cal(cal(mul(hash1, pow_base[len2])) + hash2);
}
private:
static constexpr ull MASK30 = (1ULL << 30) - 1;
static constexpr ull MASK31 = (1ULL << 31) - 1;
static constexpr ull MASK61 = (1ULL << 61) - 1;
static constexpr ull MOD = (1ULL << 61) - 1;
static constexpr ull buf = MOD * 4;
static ull BASE;
static vector<ull> pow_base;
static ull mul(ull a, ull b) {
ull au = a >> 31, ad = a & MASK31;
ull bu = b >> 31, bd = b & MASK31;
ull mid = ad * bu + au * bd;
ull midu = mid >> 30, midd = mid & MASK30;
return (au * bu * 2 + midu + (midd << 31) + ad * bd);
}
static ull cal(ull x) {
ull xu = x >> 61;
ull xd = x & MASK61;
ull res = xu + xd;
if (res >= MOD) res -= MOD;
return res;
}
static void set_hash() {
if (BASE == 0) BASE = (1UL << 31) + (random_device()() & MASK31);
}
static void extend_pow_base(int len) {
int nlen = pow_base.size();
if (nlen > len) return;
pow_base.resize(len + 1);
rep(i, nlen, len + 1) pow_base[i] = cal(mul(pow_base[i - 1], BASE));
}
string str;
int n;
vector<ull> inner_hash;
void build(const string& s) {
set_hash();
str = s;
n = s.size();
extend_pow_base(n);
inner_hash.resize(n + 1);
inner_hash[0] = 0;
rep(i, 0, n) inner_hash[i + 1] = cal(mul(inner_hash[i], BASE) + s[i]);
}
};
ull RollingHash::BASE = 0;
vector<ull> RollingHash::pow_base = vector<ull>(1, 1);
using roriha = RollingHash;
} // namespace lib