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rollinghash.hpp
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rollinghash.hpp
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#pragma once
#include "Utility/random.hpp"
struct RollingHash {
using ull = unsigned long long;
const ull MOD = 0x1fffffffffffffff;
const ull base;
vector<ull> hashed, power;
static constexpr ull mask(ll a) { return (1ULL << a) - 1; }
inline ull mul(ull a, ull b) const {
__uint128_t ans = __uint128_t(a) * b;
ans = (ans >> 61) + (ans & MOD);
if (ans >= MOD)
ans -= MOD;
return ans;
}
static inline ull genbase() { return Random::get(ull(0x1fffffffffffffff)); }
RollingHash() = default;
RollingHash(const string &s, ull base) : base(base) {
ll n = s.size();
hashed.assign(n + 1, 0);
power.assign(n + 1, 0);
power[0] = 1;
for (ll i = 0; i < n; i++) {
power[i + 1] = mul(power[i], base);
hashed[i + 1] = mul(hashed[i], base) + s[i];
if (hashed[i + 1] >= MOD)
hashed[i + 1] -= MOD;
}
}
ull get(ll l, ll r) const {
ull ret = hashed[r] + MOD - mul(hashed[l], power[r - l]);
if (ret >= MOD)
ret -= MOD;
return ret;
}
ull connect(ull h1, ull h2, ll h2len) const {
ull ret = mul(h1, power[h2len]) + h2;
if (ret >= MOD)
ret -= MOD;
return ret;
}
void connect(const string &s) {
ll n = hashed.size() - 1, m = s.size();
hashed.resize(n + m + 1);
power.resize(n + m + 1);
for (ll i = n; i < n + m; i++) {
power[i + 1] = mul(power[i], base);
hashed[i + 1] = mul(hashed[i], base) + s[i - n];
if (hashed[i + 1] >= MOD)
hashed[i + 1] -= MOD;
}
}
ll LCP(const RollingHash &b, ll l1, ll r1, ll l2, ll r2) {
ll len = min(r1 - l1, r2 - l2);
ll low = -1, high = len + 1;
while (high - low > 1) {
ll mid = (low + high) / 2;
if (get(l1, l1 + mid) == b.get(l2, l2 + mid))
low = mid;
else
high = mid;
}
return low;
}
};
/**
* @brief Rolling Hash
*/